Ophthalmic devices, system and methods that improve peripheral vision

ABSTRACT

The present disclosure relates to devices, systems, and methods for improving or optimizing peripheral vision. In particular, methods are disclosed which include utilizing particular characteristics of the retina in improving or optimizing peripheral vision. Additionally, various IOL designs, as well as IOL implantation locations, are disclosed which improve or optimize peripheral vision.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 16/025,958, filed Jul. 2, 2018 and issued as U.S.Pat. No. 10,588,739, which is a divisional of and claims priority toU.S. patent application Ser. No. 14/692,609, filed Apr. 21, 2015 andissued as U.S. Pat. No. 10,010,407, which claims the benefit under 35U.S.C. § 119(e) of U.S. Provisional Application No. 61/982,135, filed onApr. 21, 2014, titled “OPHTHALMIC DEVICES, SYSTEM AND METHODS FORIMPROVING PERIPHERAL VISION.” U.S. Pat. No. 10,010,407 also claims thebenefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No.62/038,667, filed on Aug. 18, 2014, titled “OPHTHALMIC DEVICES, SYSTEMAND METHODS FOR IMPROVING PERIPHERAL VISION.” The entire contents ofeach of the above identified applications are incorporated by referenceherein in their entirety for all it discloses and are made part of thisspecification.

BACKGROUND Field

This disclosure generally relates to devices, systems and methods thatimprove peripheral vision.

Description of Related Art

Intraocular Lenses (IOLs) may be used for restoring visual performanceafter a cataract or other ophthalmic procedure in which the naturalcrystalline lens is replaced with or supplemented by implantation of anIOL. When such a procedure changes the optics of the eye, generally agoal is to improve vision in the central field. Recent studies havefound that, when a monofocal IOL is implanted, peripheral aberrationsare changed, and that these aberrations differ significantly from thoseof normal, phakic eyes. The predominant change is seen with respect toperipheral astigmatism, which is the main peripheral aberration in thenatural eye, followed by sphere, and then higher order aberrations. Suchchanges may have an impact on overall functional vision, on myopiaprogression, and—for newborns and children—on eye development.

There are also certain retinal conditions that reduce central vision,such as AMD or a central scotoma. Other diseases may impact centralvision, even at a very young age, such as Stargardt disease, Bestdisease, and inverse retinitis pigmentosa. The visual outcome forpatients suffering from these conditions can be improved by improvingperipheral vision.

SUMMARY

The systems, methods and devices of the disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein.

Various systems, methods and devices disclosed herein are directedtowards intraocular lenses (IOLs) including, for example, posteriorchamber IOLs, phakic IOLs and piggyback IOLs, which are configured toimprove peripheral vision. For normal patients, e.g., uncomplicatedcataract patients, peripheral vision may be balanced with good centralvision in order to improve or maximize overall functional vision. Forthose patients having a pathological loss of central vision, peripheralvision may be improved or maximized, taking into account the visualangle where the retina is healthy.

In some embodiments, an IOL can be configured to reduce peripheralaberrations by tailoring parameters of the IOL according to stop-shiftequations, which are discussed in greater detail herein. The IOL can beconfigured to position its principal plane posterior (relative to thepupil) to a standard IOL's principal plane by tailoring the shape factorof the lens, the axial displacement (physical or virtual) of the lens,the index of refraction of the lens, the asphericity of one or moresurfaces of the lens, by adding an extra aperture, or any combination ofthese techniques. In various embodiments, the principal place can beshifted by a distance between about 0.1 mm and about 4.5 mm by movementof haptics. In some embodiments, the shape factor of the IOL can bealtered by altering the geometry (e.g., radius of curvature and/orthickness) or changing the refractive index of the material of the IOL.Altering the shape factor of the IOL can shift the principal plane byabout a few hundred microns. In various embodiments, shifting theprincipal plane by movement of haptics and by altering the shape factorof the lens can advantageously reduce peripheral astigmatism.

In one embodiment, the principal plane of the lens is moved posteriorly,further from the iris, which is the natural aperture at the eye, orcloser to the nodal point of the eye as compared to standard IOLs. Thiseffectively changes the field curvature in the image plane, to betteralign with the shape of the retina. In some embodiments, the axialposition of the IOL is between about 1.5 mm and about 2.5 mm behind theiris. For example, the axial position of the IOL may be about 1.9 mmbehind the iris. In certain embodiments, the axial position of the IOLis between about 2.5 mm and about 3.5 mm behind the iris. For example,the axial position of the IOL may be about 2.9 mm behind the iris.

In some embodiments, the axial position of the IOL may be between about3.5 mm and about 4.1 mm behind the iris. For example, the axial positionof the IOL may be about 3.9 mm behind the iris. For regular eyedimensions, the position of the lens may be limited by the vitreousbody, to not exceed about 4.5 mm behind the iris. For some embodimentsof the lenses used in this example, the principal plane is about 0.4 mmposterior to the anterior lens surface. The location of the principalplane posterior to the anterior lens surface can be altered by modifyingthe shape factor. For example, depending on the shape factor of thelens, the principal planes can be located placed at different distances,such as, for example, greater than or equal to 0.1 mm posterior to theanterior lens surface, greater than or equal to 0.5 mm posterior to theanterior lens surface, greater than or equal to 0.8 mm posterior to theanterior lens surface, greater than or equal to 1.0 mm posterior to theanterior lens surface, greater than or equal to 1.5 mm posterior to theanterior lens surface, greater than or equal to 1.8 mm posterior to theanterior lens surface, greater than or equal to 2.1 mm posterior to theanterior lens surface, greater than or equal to 2.5 mm posterior to theanterior lens surface, greater than or equal to 3.0 mm posterior to theanterior lens surface, greater than or equal to 3.5 mm posterior to theanterior lens surface and greater than or equal to 4.0 mm posterior tothe anterior lens surface. Therefore, when the example refers to adistance of the lens of, e.g., 1.5 mm behind the iris, it means theprincipal plane of the lens is about 1.9 mm behind the iris.

Instead of moving the lens posteriorly relative to a conventionalposition in the eye, a lens configuration may be applied that moves theprincipal plane of the lens posteriorly, while the physical lens isstill in the conventional position in the eye. One way to achieve thisis to change the shape factor of the lens, e.g., to a meniscus lenshaving a concave anterior surface and a convex posterior surface. Themeniscus lens can also advantageously reduce astigmatism. Withoutsubscribing to any particular theory, a modification of shape factor canbe achieved by changing the geometry (e.g., radius of curvature,thickness) of the lens, refractive index of the material of the lens ora combination of both. Accordingly, in some embodiments, the location ofthe principal place can be altered by increasing or decreasing thethickness of the lens. In some embodiments, the location of theprincipal place can be altered by increasing or decreasing the radius ofcurvature of the lens. In some embodiments, an intraocular lens systemof 2 lenses is used, e.g., having a negative power anterior lens and apositive power posterior lens. Those skilled in the art will appreciatethat other combinations are possible.

The lens may be a multifocal lens, a lens including a prism, or atelescope lens, having the principal plane moved posteriorly by one ofthe methods described above. In a multifocal lens, the position of theprincipal plane may be determined based on analysis using one focalpoint, several of the focal points, or all focal points of themultifocal lens. In a preferred embodiment, a multifocal IOL has atleast 2 zones, wherein the at least 2 zones have about the same opticalpower. The inner zone may be a spherical lens producing a good centralfocus. The outer zone(s) comprise of a spherical lens combined with aprism, producing a good focus at a predetermined spot in the periphery.A similar affect may be achieved if the outer zone(s) are aspheric.Alternatively, a bag-filling lens with a gradient refractive index maybe used. Such lenses can also advantageously reduce age related maculardegeneration (AMD).

In some embodiments, an artificial pupil may be implanted between thelenses of a dual lens system or posterior to an IOL or lens combination.Such an artificial pupil may have a similar impact as moving the IOLposteriorly.

In some embodiments, a singular circular surface structure, which actsas a phase shifting profile extends the depth of focus in the peripheralfield. Implementations of such structures are described in U.S. Pat. No.8,430,508, which is hereby incorporated by reference herein in itsentirety. An implementation of a single ring IOL includes an anteriorface and a posterior face. A profile can be imposed on the anterior orposterior surface or face. The profile can have an inner portion and anouter portion. The inner portion typically presents a parabolic curvedshape. The inner portion may also be referred to as a microstructure, anisolated echelette, or a central echelette. Between the inner portionand the outer portion, there may be a transition zone that connects theinner and outer portions. An IOL with such a structure provides for areduction in peripheral aberrations, including astigmatism and otherhigher order aberrations. In certain embodiments, a multifocal IOL isused to induce multiple foci. While traditional multifocal IOLs utilizemultiple foci at multiple powers, in this embodiment, the multiple fociare of the same optical power. In addition, the multiple foci focusimages on different parts of the retina, thus producing optimal opticalquality at those regions of the retina that are healthy.

In some embodiments, characteristics of the retina are considered forthe IOL design. In particular, a geographical map of retinalfunctionality and/or the retinal shape are combined with other oculargeometry, such as pupil size and location, axial positions of the pupil,lens, and retina, anterior and/or posterior corneal aberrations, tiltsand decentrations within the eye, and angle kappa. A metric function canbe used to improve or optimize the IOL, accounting for both central andperipheral optical quality. In some embodiments, the IOL powerdistribution at the periphery can be related with retinal shape.Therefore, while measuring retinal shape it might be possible to selectthe IOL with the peripheral power distribution that matches patient'sretina.

In some embodiments, a dual-optics IOL system can be used to improvenatural vision by reducing peripheral aberrations. The dual-optics lenscan comprise an anterior lens and a posterior lens. The dual-optics lenscan have a shape factor based on the optical powers of the anterior andposterior lenses, the shape factor being tailored to reduce peripheralaberration. The shape factor can be modified for each lens whilemaintaining the total optical power relatively constant. The shapefactors can be modified by adjusting the anterior and posterior radii ofcurvature of each lens, e.g., the anterior lens and the posterior lens.The shape factors can be tailored to reduce astigmatism and sphericalequivalent in the periphery of the retina while maintaining on-axisoptical quality on the retina.

In some embodiments, one or more IOLs can be used which have one or moreaspherical surfaces configured to improve peripheral vision by reducingperipheral aberrations. The asphericity of the surfaces can be tailoredto improve off-axis contrast, thereby improving peripheral visionrelative to IOLs with typical surface geometries.

In some embodiments, a method is provided for improving vision using anintraocular lens which reduces peripheral aberrations. The methodincludes determining a principal plane of an intraocular lens;determining a value of at least one peripheral aberration at the retinaof an eye based at least in part on an initial proposed placement of theprincipal plane of the intraocular lens in the eye and based at least inpart on a computer model of an eye; modifying a parameter of theintraocular lens, wherein the parameter consists of at least one of ashape factor of the intraocular lens, an axial displacement of theintraocular lens, an index of refraction of the intraocular lens, or anasphericity of the intraocular lens; comparing the value of the at leastone peripheral aberration with a value of the at least one peripheralaberration after modification of the parameter; and incorporating themodified parameter into the intraocular lens if the modificationimproves the vision of the patient by reducing the at least oneperipheral aberration.

Various implementations of the method can comprise determining amodified value of the at least one peripheral aberration aftermodification of the parameter using at least one stop-shift equation.The at least one peripheral aberration can include coma or astigmatism.The method can further comprise determining a constraint on theparameter of the intraocular lens. The intraocular lens designed usingthe method above can include a lens element which has an asphericalsurface. The asphericity of the surface of the intraocular lens can befurther modified to increase an off-axis contrast produced by theintraocular lens. In various implementations of the method modifying aparameter of the intraocular lens can include providing an additionalaperture. The method can include determining a target position of theintraocular lens in an eye of a patient, wherein the target position ofthe intraocular lens is such that the principal plane of the intraocularlens is between 1.9 mm and 4.5 mm behind the iris.

In some embodiments, a method is provided for improving vision using adual-optic intraocular lens comprising an anterior lens element havingan anterior optical power and a posterior lens element having aposterior optical power. The method includes calculating a shape factorof the intraocular lens where the shape factor is equal to the sum ofthe anterior optical power and the posterior optical power divided bythe difference between the posterior optical power and the anterioroptical power; determining a value of at least one peripheral aberrationat the retina of an eye based at least in part on the shape factor ofthe intraocular lens and based at least in part on a computer model ofan eye; modifying an anterior shape factor of the anterior lens elementby modifying an anterior radius of the anterior lens element or theposterior radius of the anterior lens element; modifying a posteriorshape factor of the posterior lens element by modifying an anteriorradius of the posterior lens element or the posterior radius of theposterior lens element; determining a modified value of the at least oneperipheral aberration at the retina of the eye based at least in part onthe shape factor of the intraocular lens and based at least in part onthe computer model of an eye; comparing the value of the at least oneperipheral aberration with the modified value of the at least oneperipheral aberration; and incorporating the modified anterior lenselement and the posterior lens element into the intraocular lens if themodification improves the vision of the patient by reducing the at leastone peripheral aberration, wherein a total optical power of theintraocular lens remains substantially unchanged after modification ofthe anterior shape factor and the posterior change factor. In variousimplementations of the dual-optic intraocular lens designed by themethod described above, a surface of the anterior lens element or asurface of the posterior lens element can be aspheric. The asphericityof the surface of the anterior lens element or the surface of theposterior lens element can be modified to increase an off-axis contrastproduced by the intraocular lens.

One aspect of the innovative aspect disclosed herein can be implementedin a dual-optic intraocular lens comprising an anterior optic and aposterior optic. The anterior optic can have an anterior optical power.The anterior optic can include a first surface with a first radius ofcurvature and a second surface opposite the first surface with a secondradius of curvature. The anterior optic can have an anterior shapefactor that is associated with the first and the second radius ofcurvature. The posterior optic can have a posterior optical power. Theposterior optic can include a third surface with a third radius ofcurvature and a fourth surface opposite the third surface with a fourthradius of curvature. The posterior optic can have a posterior shapefactor that is associated with the third and the fourth radius ofcurvature. A shape factor of the intraocular lens given by the sum ofthe anterior optical power and the posterior optical power divided bythe difference between the posterior optical power and the anterioroptical power can be optimized by optimizing the anterior shape factoror the posterior shape factor such that a degradation in the visualinformation obtained from a peripheral retinal location is below athreshold degradation. A total optical power of the intraocular lens canremain substantially unchanged after modification of the anterior shapefactor or the posterior shape factor.

In various implementations, the posterior optic can be disposed in thecapsular bag of the eye of a patient. The anterior optic can be disposedin the capsular bag of the eye of a patient or at a location between theiris and the capsular bag. In various implementations, at least one ofthe first, second, third or fourth surface can be aspheric.

In some embodiments, a method is provided for increasing contrastsensitivity function (CSF) for peripheral vision. The method includesproviding a first IOL for implanting into a first eye of the patient,the first IOL configured to increase acuity of a sagittal image; andproviding a second intraocular lens (IOL) for implanting into a secondeye of a patient, the second IOL configured to increase CSF of atangential image.

In various implementations of the method, the first IOL can beconfigured to increase contrast of the sagittal image when implanted ata first distance from the pupil. The second IOL can be configured toincrease contrast of the tangential image when implanted at a seconddistance from the pupil. The first IOL can be configured to be implantedin the first eye at a first distance from the pupil and the second IOLcan be configured to be implanted in the second eye at a second distancefrom the pupil. The first distance can be lesser than the seconddistance. A difference between the first distance and the seconddistance can be between about 0.5 mm and about 5 mm.

In some embodiments, an IOL is provided that is configured to increaseCSF in the horizontal field of view without increasing CSF in thevertical field of view to improve peripheral vision. The IOL includes atleast one toric portion and at least one non-toric portion. In variousimplementations of the IOL, the at least one toric portion can have ahigher optical power along the vertical axis than the horizontal axis.The at least one toric portion can be disposed in a central region ofthe IOL. The at least one toric portion can be disposed in a peripheralregion of the IOL. The IOL can include features that induce sphericalaberrations. The IOL can include features that induce asphericalaberrations. The IOL can include diffractive features. The IOL can beconfigured to provide astigmatic correction. The IOL can be configuredto provide extended depth of focus. The IOL can be configured to provideacuity for peripheral vision. The toric portion can improve acuity forperipheral vision along a horizontal direction.

In some embodiments, an IOL is provided that is configured to compensatefor peripheral aberrations, such as, for example, peripheral astigmatismand horizontal coma arising from light incident at oblique angles.Various embodiments of IOL that compensate for peripheral aberrationscan reduce coma and/or astigmatism in the peripheral field of view. Dueto the oblique incidence of the light in the eye, astigmatism increaseswith eccentricity. The increase in astigmatism with eccentricity followsa fixed trend. As previous studies have found, this dependence does notchange with age and/or foveal refractive errors, either for fovealsphere or astigmatism. Therefore patients can benefit from embodimentsof IOLs having an arrangement of optical features (e.g. opticalelements, grooves, volume or surface diffractive features, regions ofvarying refractive index, etc.) that results in a peripheral astigmatismthat decreases with eccentricity. The decrease in astigmatism witheccentricity for the IOL can follow an opposite trend.

Recent studies indicate that similar to peripheral astigmatism,horizontal coma is also independent of the patient's age and/or fovealrefractive errors, axial length of the cornea, corneal curvature, etc.and depends on the eccentricity or field of view according to a fixedtrend. Accordingly, errors in peripheral vision can be compensated by anIOL having an arrangement of optical features (e.g. optical elements,grooves, volume or surface diffractive features, regions of varyingrefractive index, etc.) such that the dependence of horizontal coma forthe IOL on the eccentricity or field of view has an opposite trend.

For example, in various implementations, an IOL configured to correctfor peripheral aberrations in a patient can include an arrangement of afirst set of optical features and an arrangement of a second set ofoptical features that compensate for peripheral aberrations. Thearrangement of the first set of optical features can be determined basedon the direction of incident light and independent of the sphericalpower required to achieve emmetropia. The arrangement of the second setof optical features can be determined based on the spherical powerrequired to achieve emmetropia. The arrangement of the first set ofoptical features can compensate for peripheral astigmatism and/orhorizontal coma. The arrangement of the second set of optical featurescan compensate for peripheral defocus. The arrangement of the second setof optical features can be determined based on an axial length of thepatient's eye or a curvature of the cornea.

Generally, peripheral defocus changes as a function of the fovealrefractive state. Accordingly, in various embodiments of IOLs, theamount of defocus can vary based on the refractive power of the IOL,which ultimately depends on the preoperative refractive state orpreoperative biometry of the patient. For example, since patients withhypermetropia have a different defocus distribution as compared topatients with myopia the arrangement of optical features thatcompensates for peripheral defocus will be different in both cases. As away of example, patients with hypermetropia have relative peripheralmyopia. In such patients, a higher central power of the IOL can beassociated with a lower peripheral power distribution, as compared tothe central power. On the other hand, patients with myopia tend to haverelative peripheral hyperopia. In such patients, a lower central powerof the IOL can be associated with a higher peripheral powerdistribution, relative to the central power.

Thus, the present disclosure provides a lens apparatus, system andmethod that improve peripheral visual acuity at least in part byreducing aberrations arising from light directed to peripheral or highfield angle retinal areas (sometimes referred to herein as peripheralaberration) relative to standard IOLs while maintaining good visionarising from light directed to most sensitive or low field angle orcentral retinal areas (sometimes referred to herein as central vision).

Various implementations of an IOL configured to correct for peripheralaberrations in a patient's eye can include a first optical powerdistribution that compensates for peripheral astigmatism; a secondoptical power distribution that compensates for horizontal coma inperipheral regions; and a third optical power distribution thatcompensates for defocus in the peripheral regions. The first and secondoptical power distribution can be independent of foveal refractive stateof the patient's eye and the third optical power distribution can dependon the foveal refractive state of the patient's eye and/or the IOL powerrequired for the patient to achieve foveal emmetropia. The first powerdistribution can vary nonlinearly with visual field angle. The firstpower distribution can vary quadratically with visual field angle. Thefirst power distribution can have a higher absolute value of cylinderpower at visual field angle having an absolute value greater than orequal to 10 degrees than the absolute value of cylinder power at visualfield angle having an absolute value less than 10 degrees. The firstpower distribution can have increased astigmatic correcting power in theperipheral regions and decreased astigmatic correcting power in acentral region. The second power distribution can vary linearly withvisual field angle. The second power distribution can linearly decreasefrom a first peripheral region oriented temporally to a secondperipheral region oriented nasally for left eyes and increase from afirst peripheral region oriented temporally to a second peripheralregion oriented nasally in right eyes. The third power distribution canbe configured to provide myopic correction power in the peripheralregions for a patient with emmetropia, hyperopia or low myopia. Thethird power distribution can be configured such that an absolutemagnitude of spherical optical power for visual field angles having anabsolute value greater than or equal to 10 degrees is greater than theabsolute magnitude of spherical optical power for visual field angleshaving an absolute value less than 10 degrees for a patient withemmetropia, hyperopia or low myopia. The third power distribution can beconfigured such that an absolute magnitude of spherical optical powerfor visual field angles having an absolute value greater than or equalto 10 degrees is smaller than the absolute magnitude of sphericaloptical power for visual field angles having an absolute value less thanor equal to 10 degrees for a patient with moderate or high myopia.

An innovative aspect of the subject matter disclosed herein can beimplemented in a method of compensating for peripheral aberrations. Themethod comprises determining a first optical power distribution thatcompensates for peripheral aberrations resulting from oblique incidenceof light; and determining a second optical power distribution thatcompensates for peripheral aberrations based on the patient's ocularcharacteristics. In various implementations, the second optical powerdistribution can be determined based on at least one of fovealrefractive power, an axial length of the eye or a curvature of thecornea. The second power distribution can be configured to providemyopic correction power in the peripheral regions for a patient withemmetropia, hyperopia or low myopia. The second optical powerdistribution can be determined based on the required IOL power toachieve foveal emmetropia. The second power distribution can beconfigured such that an absolute magnitude of spherical optical powerfor visual field angles having an absolute value greater than or equalto 10 degrees is greater than the absolute magnitude of sphericaloptical power for visual field angles having an absolute value less than10 degrees for a patient with emmetropia, hyperopia or low myopia. Thesecond power distribution can be configured to provide hyperopiccorrection in the peripheral regions for a patient with moderate or highmyopia. The second power distribution can be configured such that anabsolute magnitude of spherical optical power for visual field angleshaving an absolute value greater than or equal to 10 degrees is smallerthan the absolute magnitude of spherical optical power for visual fieldangles having an absolute value less than 10 degrees for a patient withmoderate or high myopia.

Various implementations disclosed herein include an IOL configured tocompensate for peripheral astigmatism in a patient. The IOL can beconfigured to provide a cylinder power with an absolute magnitude of atleast 0.5 Diopter for at least one visual field angle having an absolutevalue greater than or equal to 10 degrees. The IOL can be configured tohave a horizontal coma coefficient of at least 0.01 microns for at leastone visual field angle greater than or equal to 10 degrees in the nasalvisual field for right eyes and temporal visual field for left eyes.Alternately, the IOL can be configured to have a horizontal comacoefficient of at least −0.01 microns for at least one visual fieldangle greater than or equal to +10 degrees in the temporal visual fieldfor right eyes and nasal visual field for left eyes. Suchimplementations of an IOL can be configured to compensate for horizontalcoma.

Various implementations of an IOL described herein can be configured tocompensate for peripheral defocus. Implementations of an IOL configuredto compensate for peripheral defocus can provide defocus between about−0.1 Diopter and about +1.0 Diopter for a patient with sphericalequivalent power between about −0.5 Diopter and about +0.5 Diopter forat least one visual field angle having an absolute value greater than orequal to 10 degrees is. Implementations of an IOL configured tocompensate for peripheral defocus can provide defocus between about −0.1Diopter and about +2.0 Diopter for a patient with spherical equivalentpower between about −0.5 Diopter and about −1.5 Diopter for at least onevisual field angle having an absolute value greater than or equal to 10degrees. Implementations of an IOL configured to compensate forperipheral defocus can provide defocus between about +1.0 Diopter andabout +3.0 Diopter for a patient with spherical equivalent power betweenabout −1.5 Diopter and about −2.5 Diopter for at least one visual fieldangle having an absolute value greater than or equal to 10 degrees.Various implementations of an IOL configured to compensate forperipheral defocus can provide defocus between about +2.5 Diopter andabout +6.0 Diopter for a patient with spherical equivalent power betweenabout −2.5 Diopter and about −6.0 Diopter for at least one visual fieldangle having an absolute value greater than or equal to 10 degrees.

Various implementations of an IOL described herein can include aplurality of optical features that have an overall optical powerdistribution that compensates for peripheral rotationally andnon-rotationally symmetric aberrations. The non-rotationally symmetricaberrations can include peripheral astigmatism and horizontal coma. Therotationally symmetric aberration can include defocus. An arrangement ofsome of the plurality of optical features that compensate fornon-rotationally symmetric aberrations can be independent of thespherical power of the IOL. The arrangement of some of the plurality ofoptical features that compensate for non-rotationally symmetricaberrations can depends on whether the eye to be implanted is right orleft. An arrangement of some of the plurality of optical features thatcompensates for rotationally symmetric aberrations can depend on thespherical power of the IOL. An arrangement of some of the plurality ofoptical features that compensates for rotationally symmetric aberrationscan be different for optical powers between 0.0D and 10.0D, 10.0D and25.0D and 25.0D and 34.0D.

Various implementations of IOLs described herein can include markingsshowing the orientation of the IOL and the eye to be implanted.

Various embodiments of an IOL include a first surface that receivesincident light entering through the cornea and the natural pupil and asecond surface opposite the first surface through which incident lightexits the IOL and propagates towards the retina. In some suchembodiments, an extra aperture can be provided after (e.g., at thesecond surface or posterior to) the second surface of the IOL. Thisextra aperture can reduce the peripheral aberrations arising from thecornea. The shape of the cornea and the distance between the cornea andthe posterior surface of the IOL, which can be large in someembodiments, can enhance the extra aperture's capability of reducingperipheral aberrations arising from the cornea. The natural pupil canreduce the peripheral aberrations from the IOL itself.

An innovative aspect of the subject matter disclosed herein can beimplemented in an intraocular lens configured to improve vision for apatient's eye. The intraocular lens comprises an optic comprising afirst surface and a second surface opposite the first surface. The firstsurface and the second surface are intersected by an optical axis. Theoptic is symmetric about the optical axis. The first or the secondsurface of the optic can be aspheric. The optic is configured to focuslight incident along a direction parallel to the optical axis at thefovea to produce a functional foveal image. The optic is furtherconfigured to focus light incident on the patient's eye at an obliqueangle with respect to the optical axis at a peripheral retinal locationdisposed at a distance from the fovea. Light can be incident at one ormore oblique angles between about 1 degree and about 30 degrees. Invarious implementations, light can be incident at an oblique anglegreater than 30 degrees from example, at oblique angle upto 45 degrees,upto 60 degrees, upto 75 degrees or greater. The peripheral retinallocation can have an eccentricity between 1 and 30 degrees with respectto the optical axis. In various implementations, the peripheral retinallocation can have an eccentricity greater than 30 degrees. For example,the peripheral retinal location can have an eccentricity upto 45-50degrees with respect to the optical axis of the eye.

The optic is configured to improve image quality at the peripheralretinal location by reducing at least one optical aberration at theperipheral retinal location. The at least one optical aberration can beselected from the group consisting of defocus, peripheral astigmatismand coma. The foveal image can have a modulation transfer function (MTF)of at least 0.5 at a spatial frequency of 100 cycles/mm for both thetangential and the sagittal foci in green light for a pupil size between3-5 mm. An image formed at the peripheral retinal location can have afigure of merit of at least 0.5. In various implementations, the figureof merit can be an average MTF for a range of spatial frequenciesbetween 0 cycles/mm and 30 cycles/mm obtained at differenteccentricities between 1 and 30 degrees. The first or the second surfaceof the optic can comprise a plurality of optical features that areconfigured to reduce the at least one optical aberration.

In various implementations, the optic can be a meniscus lens with avertex curving inwards from edges of the optic. The optic can have amaximum thickness between about 0.3 mm and about 2.0 mm. In variousimplementations, the lens can be a dual-optic IOL further comprising asecond optic separated from the optic by a fixed or a variable distance.In implementations of the dual-optic IOL, wherein the distance betweenthe two optics is variable, the distance can be varied by application ofocular forces. A first optic of the dual-optic IOL can be disposed inthe capsular bag of the patient's eye, and the second optic can bedisposed between the iris and the patient's eye. Alternately, both theoptics of the dual-optic IOL can be disposed in the capsular bag of thepatient's eye.

The optic can be configured to improve image quality at the peripheralretinal location by adjusting a shape factor of the optic such that theat least one peripheral optical aberration is reduced. The shape factorof the optic can be adjusted by adjusting a parameter of the optic. Theparameter can be selected from the group consisting of a curvature ofthe first or the second surface, an axial position of the optic withrespect to the retina and a thickness of the optic.

Another innovative aspect of the subject matter disclosed herein can beimplemented in a method of selecting an intraocular lens (IOL)configured to be implanted in a patient's eye. The method comprisesobtaining at least one physical or optical characteristic of thepatient's eye using a diagnostic instrument; and selecting an IOL havinga shape factor that is configured to focus light incident along adirection parallel to the optical axis at the fovea to produce afunctional foveal image and is further configured to improve imagequality at a peripheral retinal location disposed at a distance from thefovea by reducing at least one optical aberration at the peripheralretinal location. The peripheral retinal location can have aneccentricity between 1 and 30 degrees. In various implementations, theperipheral retinal location can have an eccentricity greater than 30degrees (e.g., upto 45-50 degrees). The shape factor of the IOL can beselected based on the at least one physical or optical characteristic ofthe patient's eye. The shape factor of the IOL can be adjusted byadjusting a parameter of the optic. The parameter of the optic caninclude a curvature of the first or the second surface, an axialposition of the optic with respect to the retina and/or a thickness ofthe optic. At least one surface of the IOL can be aspheric. The opticcan be configured to provide a foveal image having a modulation transferfunction (MTF) of at least 0.5 at a spatial frequency of 100 cycles/mmfor both the tangential and the sagittal foci in green light for a pupilsize between 3-5 mm. An image formed at the peripheral retinal locationby the optic can have a figure of merit of at least 0.5. In variousimplementation, the figure of merit can be an average MTF for a range ofspatial frequencies between 0 cycles/mm and 30 cycles/mm obtained atdifferent eccentricities between 1 and 30 degrees.

BRIEF DESCRIPTION OF THE DRAWINGS

The systems, methods and devices may be better understood from thefollowing detailed description when read in conjunction with theaccompanying schematic drawings, which are for illustrative purposesonly. The drawings include the following figures:

FIG. 1 is a cross-sectional view of a phakic eye containing a naturalcrystalline lens.

FIG. 2 is a cross-sectional view of a pseudophakic eye containing anintraocular lens.

FIG. 3 is a graph illustrating peripheral astigmatism with the fieldangle in degrees and cylinder in diopters.

FIG. 4 is a graph illustrating peripheral astigmatism with the fieldangle in degrees and sphere in diopters.

FIG. 5 is a graph illustrating peripheral astigmatism with the fieldangle in degrees and higher order aberrations in micrometers.

FIG. 6 shows aspects of a lens including a ring microstructure.

FIG. 7 illustrates aspects of a diffractive lens.

FIG. 8 is a graph illustrating through-focus MTF at different axialfocus positions.

FIG. 9 is a graph illustrating through-focus MTF at different axialfocus positions.

FIG. 10 shows aspects of a multifocal IOL in an eye.

FIG. 11 depicts the astigmatism in the natural lens and animplementation of an artificial IOL as a function of eccentricity indegrees.

FIG. 12 is a graph illustrating astigmatism and coma as a function ofdisplacement of an IOL with a shape factor of 0.15.

FIG. 13 is a graph illustrating astigmatism and coma as a function ofdisplacement of an IOL with a shape factor of −1.5.

FIG. 14 is a graph illustrating the influence of shape factor onastigmatism and position of an IOL with respect to the pupil.

FIGS. 15A-D are graphs illustrating spherical equivalent, cylinder,spherical aberration, and coma as a function of field angle for avariety of IOL displacements.

FIG. 16 is a graph illustrating astigmatism and coma as a function ofdisplacement from the cornea of an additional aperture.

FIG. 17 illustrates a flow chart of an example method for tailoring IOLproperties to reduce peripheral aberrations using stop-shift equations.

FIG. 18 is a graph illustrating relative refraction at 30 degreeseccentricity as a function of shape factor for a dual opticconfiguration.

FIG. 19 is a graph illustrating relative refraction as a function ofeccentricity for a dual optic configuration.

FIG. 20A-B are graphs illustrating the impact of a global shape factorand asphericity on relative refraction for astigmatism and sphericalequivalent.

FIG. 21A-B are graphs illustrating the impact of a global shape factorand asphericity on contrast as a function of eccentricity for tangentialand sagittal directions.

FIG. 22 illustrates a flow chart of an example method for tailoring aglobal shape factor of a dual-optics IOL to reduce peripheralaberrations.

FIG. 23 shows the substantial part of the peripheral field of view thatis visible to both eyes for an implementation of an IOL implanted in theeye.

FIG. 24A is a graph illustrating the modulation transfer function (orMTF) as a function of eccentricity for sagittal and tangential visionfor an implementation of an IOL at a first axial focus position. FIG.24B is a graph illustrating MTF as a function of eccentricity forsagittal and tangential vision for an implementation of the IOL at asecond axial focus position.

FIG. 25 is a graph illustrating contrast sensitivity function in fourdifferent field directions.

FIG. 26 illustrates a comparison of the optical image quality(horizontal astigmatism) in the periphery of phakic and pseudophakiceyes.

FIG. 27 is a graph illustrating the variation of cylinder power alongthe axis oriented at 0-degrees with respect to the equator (J₀) as afunction of visual field for patients with different refractive error onaxis.

FIG. 28 is a graph illustrating the variation of horizontal coma as afunction of visual field.

FIG. 29 is a graph illustrating the variation of defocus as a functionof visual field for patients with different refractive error on axis.

FIG. 30A illustrates the through-focus MTF for an implementation of alens having a cylindrical error of about 8.4 Diopter for an image formedat a location of the peripheral retina centered at 25 degreeseccentricity in green light at 10 cycles/mm. FIG. 30B illustrates thethrough-focus MTF for an implementation of a lens having a cylindricalerror of about 1.2 Diopter for an image formed at a location of theperipheral retina centered at 25 degrees eccentricity in green light at10 cycles/mm. FIG. 30C illustrates the through-focus MTF for animplementation of a lens having a cylindrical error of about 0.75Diopter for an image formed at a location of the peripheral retinacentered at 25 degrees eccentricity in green light at 10 cycles/mm.

FIG. 31 illustrates a flowchart depicting an implementation of a methodto obtain a metric used to evaluate the peripheral image qualityprovided by an implementation of a lens.

FIG. 32 illustrates the spatial frequency that is achievable based onthe ganglion cell density at different eccentricities.

FIG. 33 shows the MTF curve for tangential and sagittal rays at aneccentricity of 20 degrees for spatial frequencies between 0 cycles/mmand 20 cycles/mm for an implementation of a lens in green light.

FIG. 34A illustrates the surface sag of a first surface of animplementation of a standard IOL and FIG. 34B illustrates the surfacesag of a second surface of the standard IOL. FIG. 34C illustrates thethrough-focus MTF at a spatial frequency of 100 cycles/mm in green lightfor a 5 mm pupil provided by the standard IOL.

FIG. 35A illustrates the surface sag of a first surface of animplementation of a meniscus IOL and FIG. 35B illustrates the surfacesag of a second surface of the meniscus IOL. FIG. 35C illustrates thethrough-focus MTF at a spatial frequency of 100 cycles/mm in green lightfor a 5 mm pupil provided by the meniscus IOL.

FIG. 36A illustrates the surface sag of a first surface of animplementation of a double aspheric IOL and FIG. 36B illustrates thesurface sag of a second surface of the double aspheric IOL. FIG. 36Cillustrates the through-focus MTF at a spatial frequency of 100cycles/mm in green light for a 5 mm pupil provided by the doubleaspheric IOL.

FIG. 37A illustrates the surface sag of a first surface of animplementation of a thick IOL and FIG. 37B illustrates the surface sagof a second surface of the thick IOL. FIG. 37C illustrates thethrough-focus MTF at a spatial frequency of 100 cycles/mm in green lightfor a 5 mm pupil provided by the thick IOL.

FIG. 38A illustrates the surface sag of a first surface of animplementation of a shifted aspheric IOL and FIG. 38B illustrates thesurface sag of a second surface of the shifted aspheric IOL. FIG. 38Cillustrates the through-focus MTF at a spatial frequency of 100cycles/mm in green light for a 5 mm pupil provided by the shiftedaspheric IOL.

FIG. 39A illustrates the surface sag of a first surface of a first opticof a dual optic IOL and FIG. 39B illustrates the surface sag of a secondsurface of the first optic. FIG. 39C illustrates the surface sag of afirst surface of a second optic of a dual optic IOL and FIG. 39Dillustrates the surface sag of a second surface of the second optic.FIG. 39E illustrates the through-focus MTF at a spatial frequency of 100cycles/mm in green light for a 5 mm pupil provided by the dual opticIOL.

FIG. 40A illustrates the surface sag of a first surface of a first opticof an accommodating dual optic IOL and FIG. 40B illustrates the surfacesag of a second surface of the first optic. FIG. 40C illustrates thesurface sag of a first surface of a second optic of the accommodatingIOL and FIG. 40D illustrates the surface sag of a second surface of thesecond optic. FIG. 40E illustrates the through-focus MTF at a spatialfrequency of 100 cycles/mm in green light for a 5 mm pupil provided bythe accommodating dual optic IOL.

FIG. 41 is a flow chart of a method of designing an IOL to compensatefor peripheral aberrations.

FIG. 42 is a flow chart of an implementation of a method to estimate theposition of an IOL or an optic implanted in the eye.

FIG. 43 is a graphical representation of the elements of computingsystem for selecting an ophthalmic lens.

DETAILED DESCRIPTION

The present disclosure generally provides devices, systems, and methodsfor improving or optimizing peripheral vision by reducing peripheralaberrations. Peripheral aberrations is a broad term and is intended tohave its plain and ordinary meaning, including, for example, aberrationswhich occur outside of the central visual field, such as from lightdirected to peripheral or high field angle retinal areas. Peripheralaberrations can include, for example and without limitation, sphericalaberrations, astigmatism, coma, field curvature, distortion, defocus,and/or chromatic aberrations. As disclosed herein, improving oroptimizing peripheral vision includes reducing peripheral aberrationswhile maintaining good on-axis visual quality, or good visual quality ator near the central visual field.

Although, the implementations described herein are directed towardsimplantable intraocular lenses; it is understood that embodimentsdisclosed herein may be applied directly, or indirectly, to other typesof ophthalmic lenses including, but not limited to, corneal implants,corneal surgical procedures such as LASIK or PRK, contact lenses, andother such devices. In some embodiments, various types of ophthalmicdevices are combined, for example, an intraocular lens and a LASIKprocedure may be used together to provide a predetermined visualoutcome. Embodiments disclosed herein may also find particular use withmultifocal or accommodating intraocular lenses.

The terms “power” or “optical power” are used herein to indicate theability of a lens, an optic, an optical surface, or at least a portionof an optical surface, to focus incident light for the purpose offorming a real or virtual focal point. Optical power may result fromreflection, refraction, diffraction, or some combination thereof and isgenerally expressed in units of Diopters. One of ordinary skill in theart will appreciate that the optical power of a surface, lens, or opticis generally equal to the refractive index of the medium (n) of themedium that surrounds the surface, lens, or optic divided by the focallength of the surface, lens, or optic, when the focal length isexpressed in units of meters.

The angular ranges that are provided for eccentricity of the peripheralretinal location in this disclosure refer to the visual field angle inobject space between an object with a corresponding retinal image on thefovea and an object with a corresponding retinal image on a peripheralretinal location.

Phakic and Pseudophakic Eyes

Embodiments disclosed herein may be understood by reference to FIG. 1 ,which is a cross-sectional view of a phakic eye with the naturalcrystalline lens, an eye 10 comprises a retina 12 that receives light inthe form of an image that is produced by the combination of the opticalpowers of a cornea 14 and a natural crystalline lens 16, both of whichare generally disposed about an optical axis OA. As used herein, an“anterior direction” is in the direction generally toward the cornea 14relative to the center of the eye, while a “posterior direction” isgenerally in the direction toward the retina 12 relative to the centerof the eye.

The natural lens 16 is contained within a capsular bag 20, which is athin membrane that completely encloses the natural lens 16 and isattached to a ciliary muscle 22 via zonules 24. An iris 26, disposedbetween the cornea 14 and the natural lens 16, provides a variable pupilthat dilates under lower lighting conditions (mesopic or scotopicvision) and contracts under brighter lighting conditions (photopicvision). The ciliary muscle 22, via the zonules 24, controls the shapeand position of the natural lens 16, which allows the eye 10 to focus onboth distant and near objects. Distant vision is provided when theciliary muscle 22 is relaxed, wherein the zonules 24 pull the naturallens 16 so that the capsular bag 20 is generally flatter and has alonger focal length (lower optical power). Near vision is provided asthe ciliary muscle contracts, thereby relaxing the zonules 24 andallowing the natural lens 16 to return to a more rounded, unstressedstate that produces a shorter focal length (higher optical power).

The optical performance of the eye 10 also depends on the location ofthe natural lens 16. This may be measured as the spacing between thecornea 14 and the natural lens which is sometimes referred to as theanterior chamber depth prior to an ocular surgical procedure, ACDpre.

Referring additionally to FIG. 2 , which is a cross-sectional view of apseudophakic eye 10, the natural crystalline 16 lens has been replacedby an intraocular lens 100. The intraocular lens 100 comprises an optic102 and haptics 104, the haptics 104 being generally configured toposition the optic 102 within the capsular bag 20, where ALP refers tothe actual lens position. Numerous configurations of haptics 104relative to optic 102 are well-known within the art and embodimentsdisclosed herein may be applied to any of these. For purposes of theembodiments disclosed herein, the location of the intraocular lens ismeasured as the spacing between the iris and the anterior surface of thelens. For example, a lens can have a principal plane that is posteriorto the anterior lens surface, e.g., a distance P. For such an examplelens, where the disclosure refers to a distance of the lens of behindthe iris, e.g., a distance L, the principal plane of the lens is adistance P+L behind the iris. To provide example values, where theprincipal plane is about 0.4 mm behind the anterior lens surface and thelens is about 1.5 mm behind the iris, the principal plane of the lenswould then be about 1.9 mm behind the iris. As discussed above, thelocation of the principal plane of the lens can vary depending on theshape factor of the IOL. Accordingly, for embodiments of lenses withdifferent shape factors, the principal plane can be located at adistance different from 0.4 mm from the anterior surface of the lens.

Placement of the Principal Plane of an IOL

In one embodiment, the principal plane of the lens is moved posteriorlyor closer to the nodal point of the eye as compared to standard IOLs. Asseen in FIGS. 3-5 , placing the IOL posteriorly improves peripheralvision. For purposes of the calculations detailed in FIGS. 3-5 an eyemodel described in the non-patent literature “Off-axis aberrations of awide-angle schematic eye model,” by Escudero-Sanz, I., & Navarro, R.“Off-axis aberrations of a wide-angle schematic eye model, J. Opt. Soc.Am. A. Opt. Image Sci. Vis., vol. 16 (8), pp. 1881-1891, 1999 was used.The entire contents of the non-patent literature are incorporated hereinby reference.

The peripheral aberrations of the natural eye were calculated accordingto this reference and are disclosed in FIGS. 3-5 as the “natural lens.”The natural lens was replaced by a standard monofocal IOL. For anaverage eye, the axial position of the principal plane of the lens istypically about 0.9 mm behind the iris. The peripheral refraction(sphere and cylinder) were then calculated for different axial positionsof the IOL (as measured from the iris). As used herein, the termperipheral refraction includes spherical and cylindrical aberrations orerrors.

The graphs show that the peripheral astigmatism is reduced considerablywhen the lens is placed further posteriorly in the eye (FIG. 3 ), whilehaving limited impact on peripheral sphere (FIG. 4 ), and higher orderaberrations (FIG. 5 ). As used herein, the term higher order aberrationsis a RMS value of higher order aberrations, such as, for example, comaand trefoil. The graphs also show that when the lens is placed about 2.9mm behind the iris (which is about 2.0 mm posterior to the currentnormal position of an IOL), the peripheral refraction (sphere andastigmatism) is about the same as that of the natural eye. As currentIOLs are located more or less at the equator of the capsular bag, aposition of 2.0 mm more posteriorly means that the lens is positionedabout against the vitreous. Since the natural lens is about 4.5 mmthick, there is space to place the IOL further posteriorly.

Various lens haptic/optic configurations may be implemented in order toplace the optic further posteriorly. For example the haptics may beanteriorly angled such that when the IOL is placed in the eye, the opticportion is vaulted posteriorly. “Virtual” posterior placement of the IOLmay be achieved by changing the shape factor of the IOL such that thedistribution power of the lens is such that more power is on theposterior side. For a single optic, for example, this can be done usinga meniscus lens, having negative power at the anterior surface andpositive power at the posterior surface. For a dual optic design, forexample, this can be achieved by having an anterior lens with a negativepower, and a posterior lens with a positive power. Increasing the lensthickness is another option disclosed herein. As will be described ingreater detail herein, moving the principal plane relative to the pupil,which acts as a stop in the eye's optical system, affects peripheralaberrations based on a framework which can be used to tailor parametersof IOL optics to reduce peripheral aberrations while maintaining goodon-axis optical quality.

Yet another option is to provide an optical system making use of 3lenses. Such lens systems are capable of optimizing field curvature, aswell as astigmatism.

In another embodiment, an artificial pupil may be implanted between thelenses of a dual lens system, or posterior to an IOL or lenscombination. Such an artificial pupil can advantageously reduceperipheral aberrations arising from the cornea.

In some embodiments, peripheral vision is improved by employingbinocular summation. To optimize peripheral vision using binocularsummation one eye is implanted with an IOL that improves or optimizessagittal image quality in the periphery, and the other is implanted withan IOL that improves or optimizes tangential image quality. Variousapproaches of the sagittal/tangential image quality improvement oroptimization are described below. One approach to improvesagittal/tangential image quality includes configuring the IOL such thatthe modulus of the optical transfer function (MTF) for sagittal rays andtangential rays is above a threshold.

In some embodiments, peripheral vision is improved by implanting an IOLwith a toric component. In various embodiments, the toric component canbe included even when the patient has good central vision and does notneed an astigmatic or toric correction and. The IOL with the toriccomponent has a higher optical power along the vertical axiscorresponding to an axis of 90-degrees using the common negativecylinder sign convention than the horizontal axis corresponding to anaxis of 180-degrees using the common negative cylinder sign convention.Such a lens can improve image quality in the horizontal field of view.This can be beneficial to patients, as most relevant visual tasks arecarried out in the horizontal field of view.

Additionally, the IOL can be configured to provide an astigmaticcorrection along the vertical and/or the horizontal axis. An astigmaticcorrection when combined with the correct higher order aberrations canprovide a good on-axis depth of focus, which can advantageously reducethe need for glasses to improve near distance vision.

Extended Depth of Focus

In another embodiment, peripheral vision is improved by an IOL designhaving an extended depth of focus in the periphery. There are severalmethods to extend the depth of focus that can be applied. Below is aspecific example, based on extending the depth of focus with a singlering microstructure.

FIG. 6 discloses a single ring microstructure for extending depth offocus as detailed in U.S. patent application Ser. No. 12/971,506 (nowU.S. Pat. No. 8,430,508), which is incorporated by reference herein inits entirety. Only half of an optical surface profile 200 of the lens isshown in FIG. 6 , although since the single ring microstructure isrotationally symmetric, the other half is a mirror image thatcomplements the lens at the left side of FIG. 6 . Profile 200 of thesingle ring surface includes an inner portion or single ring 210, a stepor transition 220, and an outer portion 230. Inner portion 210 extendsbetween a central location 270 of profile 200 and transition 220, andouter portion 230 extends between transition 220 and a peripherallocation 280 of profile 200. Central location 270 is typically disposedat the optical axis. Transition 220 is disposed at a distance of about1.5 mm from the optical axis, and peripheral location 280 is disposed atthe diameter of the clear aperture of the lens, here at a distance ofabout 3.0 mm from the optical axis. In some cases, transition 220 can bedisposed at a distance from the optical axis that is within a range fromabout 0.5 mm to about 2.0 mm, and peripheral location 280 can bedisposed at a distance from the optical axis that is within a range fromabout 2.0 to about 3.5 mm, or bigger (for example, for contact lenses,the ranges would be scaled due to the larger sizes of the contact lenscompared to an IOL).

As shown in FIG. 6 , the surface height or sag (d) from a referenceplane perpendicular to the optical axis, of each point on the lensprofile is plotted against the radial distance (r) from the optical axisof the lens. As shown here, the value of displacement or total sag (d)can have a value within a range from about 0 mm to about 0.07 mm. Thetotal sag can depend on the refractive shape of the surface and can havea value, for an IOL, of typically between 0 mm and about 2 mm, or toabout minus 2 mm, in cases where the surface is concave.

Extended Depth of Focus—Inner Portion

Inner portion or echelette 210 includes a center 210 a and a peripheraledge 210 b. At center or central section 210 a of inner portion 210, thesag (d) of inner portion 210 is substantially equivalent to thedisplacement or sag (d) of peripheral curve 260. At peripheral edge 210b, the sag (d) of inner portion 210 is substantially equivalent to thesag (d) of diffractive base curve 240. Where radial distance (r) iszero, sag (d) of inner portion 210 is equivalent to the value of theperipheral curve 260. The value of sag (d) between radial distance zeroand radial distance at the peripheral edge 210 b, for example at 1.5 mm,gradually and smoothly changes from the value of peripheral curve 260(at r=0) to diffractive base curve 240 (at 1-1.5 mm) in a parabolicfashion. As shown here, inner portion 210 can present a parabolic shape,for example as described in Equation 4a of Cohen, Applied Optics, 31:19,pp. 3750-3754 (1992), incorporated herein by reference herein in itsentirety.

Extended Depth of Focus—Transition

At the peripheral edge 210 b, where the radial distance (r) is 1.5 mm,the value of sag (d) steps or changes from the value of diffractive basecurve 240 to the value of peripheral curve 260. Where radial distance(r) corresponds to transition 220, sag (d) of inner portion 210 isequivalent to the value of the diffractive base curve 240. Relatedly,the displacement of the profile 200 approaches that of the peripheralcurve 260 as the radial distance increases from a value of zero to avalue of about 1.5 mm. The value of the offset can be determined alongthe vertical axis. The offset value may be selected depending on theamount of phase delay. According to one embodiment, the inner portion210 and the outer portion 230 may not end up at the same vertical heightat position 210 b/230 a. One way to connect these two endpoints is byusing a straight vertical line. As shown here, the diffractivetransition step provides a sharp step in the profile. In some cases thetransition is characterized by a step height having a value within arange from about 0.5 microns and about 4 microns.

Extended Depth of Focus—Outer Portion

Outer portion 230 includes an inner or central edge 230 a and aperipheral edge 230 b. At inner edge 230 a, the sag (d) of outer portion230 is substantially equivalent to the sag (d) of peripheral curve 260.At peripheral edge 230 b, the sag (d) of outer portion 230 remainssubstantially equivalent to the sag (d) of peripheral curve 260. Thevalue of sag (d) for the outer portion 230 of profile 100 between radialdistance 1.5 mm and radial distance 3.0 mm is equivalent to the value ofperipheral curve 260. The sag of the profile 200 and the peripheralcurve 260 are approximately equivalent between radial distance values of1.5 mm and 3.0 mm.

Extended Depth of Focus—Example Embodiments

In addition to a single ring, limited ring extended depth of focusembodiments, as disclosed in application Ser. No. 12/971,607, can beachieved by adding a limited number of echelettes to the above detailedsingle ring microstructure. In general such limited ring embodimentscomprise a limited number of echelettes that are either adjacent ornon-adjacent to the inner central echelette and may or may not beseparated by a refractive region. It should be appreciated that anyvariation of single and limited ring embodiments falls within the scopeof embodiments disclosed herein.

FIG. 7 provides a graphical representation of a portion of a lensdiffractive profile with a central echelette and one peripheral adjacentechelette according to some embodiments. In FIG. 7 , the height of thesurface relief profile (from a plane perpendicular to the light rays) ofeach point on the echelettes surface is plotted against the distancefrom the optical axis of the lens. The echelettes can have acharacteristic optical zone 930 and transition zone 931. Optical zone930 can have a shape or downward slope that may be linear when plottedagainst p as shown in FIG. 7 . When plotted against radius r, opticalzone 930 can have a shape or downward slope that is parabolic. Centraland peripheral echelettes can have a surface area that is between 0.7and 7 mm². For example, the echelettes may have a surface area that is0.85 mm². An outer (refractive) zone can follow the base radius with afixed offset. Example embodiments include peripheral echelette(s) thatare similar in shape (e.g., elliptical) and variable step height as thecentral echelette. Of course, this disclosure includes those embodimentswhere the peripheral echelette(s) differ in shape and/or variable stepheight as compared to the central echelette.

Extended Depth of Focus—Peripheral Aberrations

The aforementioned structures can extend the depth of focus and reduceaberrations in the peripheral field. As seen in FIGS. 8 and 9 , theextended depth of focus IOL has no significant peripheral astigmatism ascompared to a standard monofocal IOL. For the purpose of analysis, astandard monofocal chromatic IOL was used in a schematic eye model,based on the following Liou & Brennan publication: Liou, H. L., &Brennan, N. A., “Anatomically accurate, finite model eye for opticalmodeling,” J. Opt. Soc. Am. A, 14 (8), 1684-1695 1997 (which isincorporated herein in its entirety), with a retinal radius of curvatureof 12 mm, a pupil diameter of 3 mm. The through focus white light MTF at50 c/mm was calculated at the periphery and at 15 degrees eccentricityin 2 perpendicular orientations (tangential and sagittal). As seen inFIG. 8 , the peak MTF value for tangential rays and the peak MTF valuefor sagittal rays do not occur at the same axial position. In fact, asobserved from FIG. 8 , the monofocal IOL has a reduced sagittal MTF atthe tangential peak, and vice versa. This can be attributed toperipheral astigmatism. As seen in FIG. 9 , the single ring extendeddepth of focus IOL, at zero defocus, had approximately equal MTF in bothorientations, indicating a reduction in astigmatism. Thus, the monofocalIOL has greater astigmatism in the periphery as compared to the extendeddepth of focus IOL.

While other solutions may have a very specific influence on a particularperipheral wavefront aberration, an extended depth of focus in theperiphery is relatively insensitive to specific aberrations anddimensions of the eye of a particular patient. Additionally, such anextended depth of focus solution also has an increased tolerance topossible issues related to surgically induced changes of aberrations, aswell as IOL placement issues. Therefore, it can be used as aone-size-fits-all solution.

Analogously, movement of the IOL posteriorly or closer to the nodalpoint also provides for a more general solution as opposed to an IOLwhich has a particular design to address particular aberrations.

Multifocal IOLs

In another embodiment, a multifocal IOL is used to induce multiple fociof the same optical power. In other words, unlike traditional multifocalIOLs, the add power for the particular embodiment described herein isabout zero. Instead, the multiple foci focus images on different partsof the retina, thus producing optimal optical quality at those regionsof the retina that are healthy, or alternatively in a ratio thatoptimizes vision.

In some embodiments, a multifocal IOL has at least 2 zones, wherein theat least 2 zones have about the same optical power. The inner zone maybe a spherical lens producing a good central focus on the central fovea.The outer zone(s) consist of a spherical lens combined with a prism,producing a good focus at a predetermined spot in the periphery as seenin FIG. 10 . One skilled in the art will appreciate that many zonevariations are possible including, but not limited to concentric ornon-concentric variations. Additionally more than two images may beformed, and the light distribution may be varied in order to optimizevisual acuity. The multifocal lens has a small add power, typicallysmaller than about 6 diopters. Preferably, the multifocal lens has anadd power of less than about 4 diopters. In another preferredembodiment, the multifocal lens has an add power of less than about 2diopters. Preferably the add power is about equal to zero.

Similar effects may be achieved through the use of outer zone(s) whichare aspheric. Alternatively, diffractive optics may be used to inducemultiple foci on different parts of the retina with the same opticalpower. This disclosure also contemplates implementations of IOLsincluding a bag-filling lens with a gradient refractive index to achieveresults similar to the results discussed above.

Consideration of Retina Characteristics

In another embodiment, characteristics of the retina are considered forthe IOL design. In particular, a geographical map of retinalfunctionality and/or the retinal shape are combined with other oculargeometry, such as pupil size and location, axial positions of the pupil,lens, and retina, anterior and/or posterior corneal aberrations, tiltsand decentrations within the eye, and angle kappa. The shape of theretina may be measured using MRI, tomography, or other techniquesapparent to those skilled in the art. A metric function can be used toimprove or optimize the IOL design, where the metric function includesboth central and peripheral optical quality. Optical quality is measuredtaking into account any particular damage to the fovea or other regionof the retina. For example, the size and location of a possible retinalscotoma may be determined. If the patient has a central scotoma whichcovers the entire fovea, then maximizing visual acuity in the peripheralregion would be included into the optical design.

Such maximization of peripheral vision would be dependent on theperipheral threshold MTF, which depends ganglion cell size and spacing.For example, the large ganglion cell size seen in the periphery limitsthe spatial resolution. Thus, improving the optical quality at spatialfrequencies beyond the sampling limit cutoff imposed by the ganglioncells would not improve resolution acuity. Therefore, any optimizationprocedure for resolution can be limited to be below that cutofffrequency.

However, if detection acuity is considered, optimization beyond theretinal cutoff frequency is beneficial for peripheral vision.

Additionally, recent data suggests that peripheral optics in myopesdiffers from that in emmetropes. For example, myopes can have relativeperipheral hyperopia, whereas emmetropes can have relative peripheralemmetropia or relative peripheral myopia. Thus, customizing an IOL toaccount for particular peripheral aberrations while balancing peripheralMTF may lead to improved overall vision.

Improving Peripheral Vision Provided by IOLs

As discussed above, a human eye can suffer from many impairments, suchas, for example presbyopia, myopia, hypermetropia, degraded peripheralvision, etc. A patient suffering from presbyopia has reduced ability tofocus on objects at near distance. Patients implanted with IOLs tocorrect for various impairments can have degraded peripheral vision(relative to a natural eye) caused by the IOL due to off-axisastigmatism, peripheral defocus, and higher order aberrations such ascoma. As used herein, on- and off-axis refer respectively to being on(e.g., along or near) or off (e.g., away from) the optical axis of theeye or the center of vision (e.g., the fovea). FIG. 11 depicts theastigmatism in the natural lens and an implementation of a typical IOLas a function of eccentricity in degrees. As used herein, eccentricityrefers to the angular distance from the center of the visual field, suchas for example, the central fovea. The curve represented by thereference numeral 1105 depicts the astigmatism in the natural lens as afunction of eccentricity and the curve represented by the referencenumeral 1110 depicts the astigmatism in an implementation of a typicalIOL as a function of eccentricity. As observed from FIG. 11 , the curve1110 has lower optical power at higher values of eccentricity ascompared to the curve 1105 indicating that implementing a typical IOLdegrades peripheral vision of the recipient as compared to the naturallens. Degraded peripheral vision can result in optical errors ondetection acuity, low contrast resolution acuity, and contrastsensitivity function in the periphery. Degraded peripheral vision mayadversely affect daily tasks where good peripheral vision is needed,such as scene gist recognition, car driving and locomotion. Accordingly,there is a need for improving the peripheral vision provided by typicalIOLs.

Several methods of improving peripheral vision provided by IOLs arediscussed herein. For example, peripheral vision can be improved by anIOL design having an extended depth of focus in the periphery asdiscussed above. As another example, peripheral vision can be improvedby tailoring parameters of the IOL based on calculations of peripheralaberrations using stop-shift equations (discussed below) which can beused to calculate aberrations resulting from lens modifications whichalter the relative displacement of an aperture (e.g., the pupil) and theprincipal plane of the lens. As another example, peripheral vision canbe improved by modifying a shape factor and/or asphericity of adual-optic lens IOL to reduce peripheral aberrations while maintainingsubstantially constant the total optical power of the IOL. As anotherexample, peripheral vision can be improved through the use of binocularsummation by implanting an IOL that optimizes sagittal image quality inthe periphery in one eye and implanting another IOL that optimizestangential image quality in the other eye. Peripheral vision can also beimproved by configuring the implanted IOL to be at least partially toricso as to provide an astigmatic correction in the horizontal visualfield. These approaches are discussed in further detail below.

Using Stop-Shift Equations to Tailor IOLs

Image quality produced by artificial IOLs, and particularly off-axisimage quality, can be improved or optimized by varying differentparameters of the IOL. The variation of such parameters can improveoff-axis image quality by reducing peripheral aberrations whilemaintaining good on-axis image quality. Examples of parameters that canbe tailored to improve peripheral vision after implantation of an IOLinclude, for example, a shape factor of the lens, through geometricalradius and material refractive index or indexes, axial displacement ofthe lens or the lens' principal plane, additional apertures, or anycombination of these. Modifying one or more of these parameters canconsequently modify a position of the principal plane of the lens withrespect to the aperture. Displacement of the principal plane of the lensrelative to an aperture affects aberrations in the optical system. Theseeffects on the aberrations can be modeled and predicted using a set ofequations called stop-shift equations which provide a theoreticalframework for predicting changes to aberrations when distances changebetween apertures (e.g., the pupil) and refractive surfaces (e.g., IOLlens elements, cornea, etc.). Accordingly, modifications can be tailoredto improve or optimize one or more peripheral aberrations to improveperipheral vision relative to a typical IOL while accounting for othervisual tradeoffs such as on-axis image quality.

The stop-shift equations provide a framework for calculating aberrationscaused by relative movements of apertures and refractive surfaces (whichincludes movement of a principal plane of a lens). Without subscribingto any particular theory, the Seidel aberrations provided in Table 1describe aberrations for a single thin lens placed in air.

TABLE 1 Wave Aberration Seidel Coefficient Aberrations Name W₀₄₀ ⅛S′_(I) Spherical Aberration W₁₃₁ ½ S′_(II) Coma W₂₂₂ ½ S′_(III)Astigmatism W₂₂₀ ¼ S′_(III) + S′_(IV)) Field Curvature W₃₁₁ ½ S′_(V)Distortion δ_(λ)W₀₂₀ ½ C′_(L) Long. Chromatic Aberration δ_(λ)W₁₁₁C′_(T) Lat. Chromatic Aberration

Table 2 expresses the Seidel aberrations as a function of structuralcoefficients of a lens (σ_(i)′). The structural coefficients change whena lens is displaced with respect to an aperture. This change isdescribed by the stop-shift equations, listed in Table 3.

TABLE 2 Seidel Aberration Structural Coefficient S′_(I) ¼ h⁴K³σ′_(I)S′_(II) ½ Lh²K²σ′_(II) S′_(III) L²Kσ′I_(II) S′_(IV) L²Kσ′_(IV) S′_(I)(2/h²)L³σ′_(V) C′_(L) h²Kσ′_(L) C′_(T) 2Lσ′_(T)

TABLE 3 Remote Stop Stop at Lens σ′_(I) σ_(I) σ′_(II) σ_(II) + Xσ_(I)σ′_(III) σ_(III) + 2Xσ_(II) + X²σ_(I) σ′_(IV) σ_(IV) σ′_(V) σ_(V) +X(σ_(IV) + 3σ_(III)) + 3X²σ_(II) + X³σ_(I) σ′_(L) σ_(L) σ′_(T) σ_(T) +Xσ_(L)

Table 4 includes structural coefficients for a thin lens in air when thestop is at the lens. In Table 4, X is the shape factor of the lens(generally calculated as (R_(p)+R_(a))/(R_(p)−R_(a)) where R_(a) is theradius of curvature of the anterior surface of the lens and R_(p) is theradius of curvature of the posterior surface of the lens), Y is theconjugate factor (generally calculated as (1/L1−1/L2)/(1/L1+1/L2), whereL1 is the distance to the object and L2 is the distance to the image. Inmost cases considered, the object is assumed to be at infinity, whichsimplifies the equation so that Y=−1, n is the index of refraction ofthe lens. Table 5 expresses certain material coefficients in terms ofthe index of refraction of the lens.

TABLE 4 Structural Coefficient Value σ_(I) AX² + BXY + CY² + D σ_(II)EX + FY σ_(III) 1 σ_(IV) 1/n σ_(V) 0 σ_(L) 1/V σ_(T) 0

TABLE 5 Material Coefficient Value A (n + 2)/[n(n − 1)²] B [4(n +1)]/[n(n − 1)] C (3n + 2)/n D n²/(n − 1)² E (n + 1)/[n(n − 1)] F (2n +1)/n

The stop shift factor, χ, is given by the equations below, where s isthe distance between the surface and the aperture stop, which can beshifted. Ks is the power of the surface, cornea or IOL underconsideration. It is noted that s>0 refers to the case of the aperturebeing placed behind the refracting surface or lens.χ=−K _(s)/[(1+Y)K _(s)+2] for s<0χ=K _(s)/[(1−Y)K _(s)−2] for s>0

These equations can be adapted for use in mediums other than air. Forexample, optical properties of a system with multiple refractingsurfaces can be tailored or optimized when it is immersed in anothermedium other than air. For the change of medium, the followingsubstitution can be made: n=n_(lens)−n_(aqueous)+1. For the multiplesurfaces, the cornea can also be taken into account.

As shown by Tables 1-3, spherical aberration is unaffected by shifts inthe stop position. As shown in Tables 4 and 5, spherical aberrationdepends on the relevant structural parameters. Coma is affected bymovement when the lens has spherical aberration in the non-displacedstate. Astigmatism is affected, provided there is coma or sphericalaberration in the non-displaced state. Accordingly, there can be comapresent which is eliminated by a shift in the relative stop position,which still supports a reduction in peripheral astigmatism. As such,both coma and astigmatism can potentially be removed by tailoring thestructural parameters and/or relative stop position of an IOL.

As can be seen from the tables and the stop-shift equations, the shapefactor, X, is a parameter which affects many aberrations. As areference, the shape factor for a symmetrical lens is 0, a plano-convexlens has a shape factor of −1 or 1 (depending on its orientation), and ameniscus lens has a shape factor that is less than −1 or greater than 1.Accordingly, it can be advantageous to determine which shape factorsprovide greater reductions in peripheral aberrations.

Referring now to FIGS. 12 and 13 , the effects of the displacement ofIOLs with different shape factors are illustrated. The graphs wereproduced using computer simulations based on the stop-shift conceptsdescribed herein. The graphs 1200 and 1300 show astigmatism and coma asa function of displacement of an IOL for an IOL having a shape factor of0.15 (graph 1200) and a shape factor of −1.5 (graph 1300).

A typical IOL has a shape factor of about 0.15, so FIG. 12 illustratesthe behavior of a typical IOL when it is displaced from an aperture.Astigmatism, line 1205, is plotted against the left-hand axis 1210, andcoma, line 1215, is plotted against the right-hand axis 1220. Asdisplacement increases, both astigmatism and coma approaches zero. Asstated herein, the lens cannot be displaced much more than 5 mm withrespect to the iris in a typical patient.

An IOL with a meniscus shape (e.g., shape factor of −1.5) improvesperformance with respect to astigmatism and coma relative to the typicalIOL, as shown in FIG. 13 , when requiring a smaller displacement forreducing astigmatism and coma. Astigmatism, line 1305, and coma, line1315, both pass zero at particular values of displacement. By reachingnegative astigmatism, the IOL can be configured to reduce or removeastigmatism caused by the cornea.

An improved or optimal displacement would be one where peripheralaberrations, such as astigmatism and coma, are reduced the most oreliminated, or where a combined aberration factor is reduced orminimized. The combined aberration factor can be a weighted sum oraverage of the various aberrations that are discussed herein. In someembodiments, finding an improved or optimized displacement includesaccounting for both off- and on-axis image quality. The considerationsfor finding or calculating an improved or optimal displacement presentedin this paragraph apply for finding improved or optimal shape factors orany other parameters of the IOL discussed herein.

As evidenced by FIGS. 12 and 13 , the shape factor affects the optimaldisplacement which reduces or eliminates one or more peripheralaberrations. To investigate the effect the shape factor has on optimaldisplacement, FIG. 14 shows a graph 1400 of the influence of shapefactor on astigmatism and an optimal position of an IOL. The optimaldisplacement of the IOL can be defined, in the graph 1400, as thedisplacement which maximizes astigmatism correction (or minimizesastigmatism induction) for a given shape factor. In some embodiments,the optimal displacement can be defined as the displacement which mostreduces the induction of coma, spherical aberration, field curvature,distortion, chromatic aberration, or any combination of these. There areconstraints on the amount of improvement or optimization based onconstraints of the system, such as a maximal displacement due to thegeometry of the eye. For example, an IOL can have a maximum displacementof about 5 mm in a typical eye, as described herein. With thatconstraint imposed, there is a limit on the amount of astigmatismcorrection that can be achieved. However, making the shape factor morenegative reduces the need for displacement from the iris to maintainastigmatism correction. Accordingly, FIG. 14 illustrates that as theshape factor increases from −4 to zero, the optimal displacement, shownas curve 1415 plotted against axis 1420, increases from 0 mm to 5 mm.When the shape factor becomes greater than −1, the astigmatism, shown ascurve 1405 plotted against axis 1410, begins to increase. This indicatesthat a meniscus lens with a negative shape factor (e.g., a shape factorof less than −1) can provide astigmatism correction while beingdisplaced less than 5 mm from the iris.

Ray tracing simulations were performed using eye models implanted witheither lenses representing a typical IOL (e.g., a shape factor of about0.15) and with a reverse meniscus IOL (e.g., a shape factor of 1.5).Table 6 shows the spherical equivalent (SE), cylinder (CYL), coma, andspherical aberration (SA) calculated for the complete eye model at 20degrees eccentricity for different IOL displacements with respect to thepupil. The first distance was set to represent a typical IOL positionwith respect to the pupil (e.g., about 0.9 mm), while an additional 2 mmdisplacement with respect to the pupil was also considered. For bothshape factors, a displacement of 2 mm reduced ocular cylinder (CYL) andcoma with respect to the original IOL position.

TABLE 6 0.9 mm 2.9 mm 20 degrees (displacement) (displacement) X = 0.15SE = −1D SE ~0 CYL = −2D CYL = −1D coma = 0.25 um coma = 0 um SA ~0 SA =0.07 um X = −1.5 SE = 0D SE = 2D CYL = −1.2D CYL = −0.4D coma = −0.7 umcoma = −0.66 um SA = 0.08 um SA = 0.02 um

Simulations were performed on the impact of the physical displacement ofa typical IOL when implanted in a model eye. The ocular aberrations fordifferent field angles and IOL positions with respect to the pupil areshown in FIGS. 15A-D. With a displacement of about 2 mm with respect toa typical IOL position (e.g., about 0.9 mm with respect to the pupil),the IOL design with a shape factor of 0.15 provides a similar peripheralcylinder as the typical crystalline lens, but without inducing sphere orcoma. This illustrates that, even for a non-meniscus IOL (e.g., an IOLwith a shape factor close to 0), physical displacement of the lens fromthe iris or pupil can be tailored to reduce or eliminate peripheralaberrations relative to the typical placement.

A range of lens characteristics can be varied to improve or optimize theresulting image quality for both on- and off-axis images. For example,to reduce astigmatism and coma, lens displacement, lens shape factor,spherical aberration or asphericity of the lens, index of refraction ofthe lens, lens thickness, or any combination of these can be configuredto improve or optimize peripheral vision. Generally, lens displacementimproves astigmatism and coma as it increases (e.g., away from theiris). Similarly, some specific lens shape factors improve astigmatismand coma as it decreases (e.g., a more negative shape factor is better).Likewise, having either a high positive spherical aberration (e.g., toprovide an increase in the stop-shift effect) or a high negativespherical aberration (e.g., to compensate corneal spherical aberration)is preferable. For the index of refraction, generally a lower valuereduces the need for increased lens displacement. In addition, agradient index-type lens with several indices of refraction improvesperipheral aberrations. Finally, a thicker lens generally gives a betterperipheral effect. Implementations of different lens designs that canreduce at least one peripheral optical aberration are discussed indetail below.

In some embodiments, a customized procedure for each patient can beimplemented which changes one or more lens characteristics (e.g.,peripheral power, peripheral astigmatism), to suit the shape of thepatient's retina. Such a procedure is described with greater detailherein with reference to FIG. 42 .

In some embodiments, an additional aperture is inserted at the plane ofthe IOL. The introduction of the additional aperture does notnecessarily reduce the astigmatism and coma of the IOL itself. However,it can decrease the astigmatism and coma that arises by obliqueincidence on the cornea itself. This effect increases with distancebetween the cornea and the additional aperture. In certain embodiments,a maximum or optimal effect is achieved when the additional aperture isbetween about 5 mm and 6 mm from the cornea. This value for optimaldisplacement depends on the optical power of the cornea. This isillustrated in FIG. 16 which shows a graph 1600 of astigmatism, curve1605 plotted against axis 1610, and coma, curve 1615 plotted againstaxis 1620, as a function of displacement of the additional aperturewhere the IOL has a shape factor of 1.3. As illustrated by the graph1600, astigmatism is at a minimum and coma is closest to 0 at adisplacement of about 5 mm to 6 mm. This demonstrates that it may bebeneficial to introduce an additional aperture after the IOL because thepupil position which provides increased performance in reducingastigmatism and/or coma is about 5-6 mm behind the cornea, differentfrom the position of the natural pupil.

The stop-shift equations, placement of additional apertures, and relatedconcepts described herein can be applied to other IOL types, including,for example and without limitation, bi- or multi-focal IOLs,accommodative IOLs, or IOLs with filters.

In some embodiments, an additional aperture can be introduced in themiddle of a dual optical system comprising two lenses with the sameabsolute value of shape factor but with opposite signs (i.e., onepositive and one negative, or both 0). For such a configuration, coma,distortion, and transversal chromatic aberration are zero based at leastin part on the symmetry of the optical system. Accordingly, in certainembodiments elements behind an aperture stop can be configured to bemirror images of those ahead of the stop, where the optical systemfunctions in unit magnification. In some embodiments, the IOL opticalsystem can be designed to be symmetrical when placed in a patient's eye,e.g., being symmetric with the cornea, the shape factor (e.g., about−1.3), and the position with respect to the pupil.

FIG. 17 illustrates a flow chart of an example method 1700 for tailoringIOL properties to reduce peripheral aberrations using the stop-shiftequations. The method 1700 can be performed using a computer configuredto execute instructions, as described herein with reference to FIG. 43 .A patient's peripheral contrast sensitivity can be improved or optimizedwhen the patient receives an IOL tailored according to the method 1700,where the improvement is relative to a typical IOL (e.g., a shape factorof about 0.15) implanted at a typical distance from the iris (e.g.,about 0.9 mm).

In block 1705, a computer model can be used to simulate or determineperipheral aberrations at a retina of a patient with the IOL. Theperipheral aberrations can be considered for different eccentricities,field angles, and the like. The peripheral aberrations can be one ormore of the aberrations chose from the group consisting of sphericalaberrations, coma, astigmatism, defocus, field curvature, distortion,longitudinal chromatic aberration, or lateral chromatic aberration. Insome embodiments, a combination of peripheral aberrations can becomputed which comprises a weighted sum or weighted average ofaberrations. The weighting of the aberrations can be done based at leastin part on its contribution to loss of peripheral contrast sensitivity.

Various parameters of the IOL such as the shape factor and/or theplacement of the principal plane can be varied to reduce the determinedperipheral aberrations. This can be accomplished in several ways. Forexample, in the illustrated method 1700, various constraints on theplacement and shape factor of the IOL are determined as shown in block1710 and the stop-shift equations described herein are used to determinea combination of placement and shape factor that reduces peripheralaberrations as shown in block 1715.

Another example of determining parameters of the IOL that reduceperipheral aberrations can include starting with an initial shape factorof the IOL and an initial position of the principal plane. Keeping theposition of the principal plane fixed, the initial shape factor of theIOL given by the stop-shift equations can be changed to a new shapefactor that reduces the peripheral aberrations. Various parameters ofthe lens such as radius of curvature of the lens, thickness of the lens,refractive indices of the material of the lens can be varied to obtainthe final shape factor for the IOL. The principal plane can be shiftedto a new position and the shape factor of the IOL can be varied until anew combination of the position of the principal plane and shape factorof the IOL is obtained that further reduces the peripheral aberrations.This process can be repeated iteratively until a combination of positionof the principal plane and shape factor of the IOL is obtained thatreduces the peripheral aberrations to a threshold or acceptable value orrange (e.g., minimizes the peripheral aberrations).

Yet another example of determining parameters of the IOL that reduceperipheral aberrations can include starting with an initial shape factorof the IOL given by the stop-shift equations and an initial position ofthe principal plane. Keeping the initial shape factor of the IOL fixed,the initial position of the principal plane can be changed to a newposition of the principal plane that reduces the peripheral aberrations.The position of the principal plane can be varied in a range around theinitial position of the principal plane. The principal plane can beshifted to the new position and the shape factor of the IOL can bevaried until a new combination of the position of the principal planeand shape factor of the IOL is obtained that further reduces theperipheral aberrations. This process can be repeated iteratively until acombination of position of the principal plane and shape factor of theIOL is obtained that reduces the peripheral aberrations to a thresholdor acceptable value or range (e.g., minimizes the peripheralaberrations).

If image quality improves based at least in part on a reduction ofperipheral aberrations, then the modified IOL can be used in place ofthe previous IOL. This process can be iterated any number of timesand/or until an optimal or acceptable IOL is produced. An optimal IOLcan be an IOL which minimizes one or more peripheral aberrations (or aweighted combination of aberrations). An acceptable IOL can be an IOLwhich improves visual acuity based on a determined, selected, or desiredthreshold of performance, where the threshold of performance can bebased at least in part on one or more peripheral aberrations (or aweighted combination of aberrations).

Dual-Optics IOL and Asphericity

In some embodiments, a dual-optics IOL design can be configured toreduce astigmatism and spherical equivalent in a periphery whilemaintaining good on-axis optical quality. The dual-optics IOL comprisesan anterior lens and a posterior lens, where anterior and posterior arerelative to the position of the iris. The anterior lens includes ananterior surface and a posterior surface and the posterior lens includesan anterior surface and a posterior surface. In some embodiments, one ormore of the surfaces of the anterior and/or posterior lens can bemodified to be aspherical, which may also reduce peripheral refraction.Accommodating and non-accommodating implementations of dual-optic IOLsincluding one or more aspheric surfaces are described below.

In the dual-optics IOL design, the global shape factor of the IOL can bemodified to reduce peripheral refraction. Analogous to a single lenswhere the shape factor is equal to (R_(p)+R_(a))/(R_(p)−R_(a))(described herein above), the global shape factor of a dual-optics IOLcan be defined as (P_(p)+P_(a))/(P_(p)−P_(a)) where P_(p) is the powerof the posterior lens and P_(a) is the power of the anterior lens. Theshape factor for each individual lens can be modified while keeping thetotal optical power constant. The shape factor for each lens can bemodified by adjusting the anterior and/or posterior surface of therespective lens.

Computer simulations utilizing eye models and ray tracing, as describedherein, can be used to determine the effects of the shape factor on bothastigmatism and spherical equivalent in periphery. With reference toFIG. 18 , graph 1800 illustrates relative refraction at 30 degreeseccentricity as a function of shape factor. The box 1805 labeled“original design” includes a single lens design with a typical shapefactor. The box 1810 on the left is for an IOL with a modified shapefactor of −1.268 and with the same optical power as the “originaldesign” which results in a reduction of astigmatism of 2.6D andspherical equivalent of 0.4D. The astigmatism and spherical equivalentcalculations are based on a maximum of a modulation transfer functionutilizing a focusing frequency of 50 c/mm. Each point on the graph 1800is for an IOL with the same optical power as the “original design.” Thisillustrates that modifying the shape factor while maintaining the sameoptical power provides an improvement in peripheral refraction.

For a dual-optics IOL design, the results are similar to those for thesingle lens design in graph 1800. For example, FIG. 19 shows graphs 1900a and 1900 b of the relative refraction as a function of eccentricityfor a dual-optics design. Graph 1900 a illustrates the effect onastigmatism for two shape factors, the first shape factor is −0.4342represented by curve 1905 a, and the second shape factor is −8.3487represented by curve 1910 a. As the eccentricity moves away from 0degrees, the dual lens design with the second shape factor demonstratesan improved astigmatism because the absolute value of the relativerefraction is less than that of the IOL with the first shape factor.Similar behavior is observed for spherical equivalent where the firstshape factor represented by curve 1905 b has a spherical equivalent thatis further from 0 when compared to the IOL with the second shape factorrepresented by curve 1910 b as the eccentricity moves away from 0degrees. As seen in the graphs 1900 a and 1900 b, the modified shapefactor for the dual lens design reduces astigmatism by 2.2D andspherical equivalent by 0.6D at 30 degrees eccentricity (e.g., whentaking the difference of the absolute values of the relative refractionvalues). As with the single lens, the total optical power of the duallens designs is configured to remain the same with the modification ofthe shape factor. Maintaining the total optical power to besubstantially same for one or more configurations of the dual lensdesign provides good on-axis visual quality.

In addition to modifying the shape factor to reduce or minimizeperipheral aberrations, either surface of each of the anterior and/orposterior lens can be aspherical with asphericity terms tailored toimprove the contrast off-axis. FIGS. 20A-B demonstrate comparativeresults when asphericity terms are assigned to the anterior surface ofeach lens (anterior and posterior lenses, each with similar asphericityin this example). FIG. 20A contains a graph 2000 a of astigmatism andFIG. 20B contains a graph 2000 b of spherical equivalent, both of whichdemonstrate the effect of shape factor and asphericity on relativerefraction. The astigmatism is reduced by 2.5D and the sphericalequivalent is reduced by 0.6D at 30 degrees eccentricity compared to theoriginal design. The respective lines 2010 a and 2010 b represent the“original design,” having a shape factor of −0.4342 and no asphericity.The respective lines 2005 a and 2005 b represent a modified design witha modified shape factor of −8.3487 and asphericity where the asphericsurfaces of each individual lens is given by the equation:

${Z(r)} = {\frac{\frac{r^{2}}{R}}{1 + \sqrt{1 - \frac{r^{2}\left( {{cc} + 1} \right)}{R^{2}}}} + {{AD} \cdot r^{4}} + {{AE} \cdot r^{6}}}$where R is the anterior radius of curvature, Z is the direction of theoptical axis, r is perpendicular to the Z-axis, cc is the conicalconstant, and AD and AE are coefficients for higher order terms. For themodified design, cc is −1.0228, AD is −7.26e-4, and AE is −9.26e-6.

Similarly, FIGS. 21A-B demonstrate the impact of shape factor andasphericity on contrast, where contrast is expressed as the maximum of amodulation transfer function. Whereas the modulation transfer functionis similar for on-axis values, the maximal off-axis values are higher inboth tangential (graph 2100 a) and sagittal (graph 2100 b) directionswhen the shape factor is tailored to improve contrast and theasphericity terms are added on both lenses of the dual-optics IOL, asdescribed herein. The respective lines 2110 a and 2110 b represent the“original design,” having a shape factor of −0.4342 and no asphericity.The respective lines 2105 a and 2105 b represent a modified design witha modified shape factor of −8.3487 and asphericity where the asphericsurfaces of each individual lens is given by the equation andcoefficients above. For the graphs in FIGS. 2000A-B and 2100A-B, thefocusing frequency used in the modulation transfer function calculationsis 10 c/mm using a 5 mm aperture.

FIG. 22 illustrates a flow chart of an example method 2200 for tailoringa shape factor of a dual-optics IOL to reduce peripheral aberrations.The method 2200 can be performed using a computer configured to executeinstructions, as described herein with reference to FIG. 43 . Apatient's peripheral contrast sensitivity can be improved or optimizedwhen the patient receives a dual-optics IOL with a shape factor tailoredaccording to the method 2200, where the improvement is relative to atypical IOL or a dual-optic IOL with a typical shape factor.

The step 2205 includes calculating a shape factor of the IOL. The shapefactor of the IOL depends on the optical power of the anterior andposterior lenses in the dual-optic IOL, as described herein.

In step 2210, a computer model can be used to simulate or determineperipheral aberrations at a retina of a patient with the dual-optic IOLof step 2205. The peripheral aberrations can be considered for differenteccentricities, field angles, and the like. The peripheral aberrationscan be one or more of the aberrations chose from the group consisting ofspherical aberrations, coma, astigmatism, field curvature, distortion,longitudinal chromatic aberration, or lateral chromatic aberration. Insome embodiments, a combination of peripheral aberrations can becomputed which comprises a weighted sum or weighted average ofaberrations. The weighting of the aberrations can be done based at leastin part on its contribution to loss of visual acuity.

In step 2215, the shape factor of the dual-optics IOL are modified tochange the peripheral aberrations. As tested in step 2225, the totaloptical power of the dual-optic IOL can be configured to remain constantwhen changes are made to the shape factor.

In step 2220, the performance of the modified dual-optic IOL (asmodified in step 2215), is compared to the dual-optic IOL of theprevious iteration. If image quality improves based at least in part ona reduction of peripheral aberrations, then the modified IOL can be usedin place of the previous IOL. This process can be iterated any number oftimes and/or until an optimal or acceptable IOL is produced. An optimalIOL can be an IOL which minimizes one or more peripheral aberrations (ora weighted combination of aberrations). An acceptable IOL can be an IOLwhich improves peripheral contrast sensitivity based on a determined,selected, or desired threshold of performance, where the threshold ofperformance can be based at least in part on one or more peripheralaberrations (or a weighted combination of aberrations).

In step 2225, the total optical power of the dual-optic IOL is computed.If the total optical power changes, the method 2200 returns to step 2215to modify the shape factor to maintain a constant total optical power.

In step 2230, when an acceptable or optimized dual-optic IOL has beendetermined, the dual-optic IOL can be implanted into a patient's eye toimprove the patient's vision by reducing peripheral aberrations relativeto a typical IOL.

In some embodiments, the method 2200 can be implemented for an IOL withmore than two lenses. In some embodiments, the method 2200 can includean additional step of modifying the asphericity of one or more surfacesof the anterior and/or posterior lenses. With such modifications, asimilar procedure is followed where the effects on the peripheralaberrations are verified to improve peripheral refraction effects andthe total optical power is verified to remain constant.

Binocular Summation to Improve Peripheral Vision

Image quality produced by artificial IOLs can be optimized by varyingdifferent design parameters such as index of refraction of the materialof the IOL, radii of curvature, asphericity, etc. In variousimplementations of artificial IOLs it may not be practical tosimultaneously optimize the acuity for central vision as well contrastsensitivity for peripheral vision due to the limited available degreesof freedom. Accordingly, in such implementations, optimizing the acuityfor central vision could degrade the acuity for peripheral vision.Furthermore, due to limited available degrees of freedom, it may not bepractical to remove all peripheral astigmatism, coma and peripheraldefocus even when performing optimization procedures solely forperipheral vision. The methods and systems described herein can usebinocular summation to overcome visual losses caused by peripheralaberrations.

Without subscribing to any particular theory, humans have a forwardfacing horizontal field of view of approximately 190 degrees with twoeyes, approximately 120 degrees of which makes up the binocular field ofview (i.e., seen by both eyes). FIG. 23 represents the forward facinghorizontal field of view. The forward facing horizontal field of viewincludes a central region 2305 that represents the binocular field ofview and edge regions 2310 that represents the monocular field of view(i.e., seen by one eye). In general the binocular field of view includesthe peripheral field of view used for most daily tasks. Thus optimizingvisual acuity in the binocular field of view can increase the contrastsensitivity for peripheral vision as well.

One approach to increase contrast sensitivity in the binocular field ofview is to implant a first IOL in one eye that is adapted to viewtangential targets (targets in the tangential plane) better than thesagittal targets and a second IOL in another eye that is adapted to viewsagittal targets (targets in the sagittal plane) better than thetangential targets. For example, in the horizontal visual field, theleft eye could be implanted with an IOL that is better at seeingvertical lines whereas the right eye could be implanted with an IOL thatis better at seeing horizontal lines. The brain combines the informationreceived from the first and the second eyes through binocular summationsuch that the combined vision has more contrast sensitivity than thevision provided by one eye alone.

In various embodiments, visual acuity in the binocular field of view canbe increased by implanting an IOL that is optimized to provide increasedcontrast sensitivity in the sagittal plane in a first eye and byimplanting an IOL that is optimized to provide increased contrastsensitivity in the tangential plane in a second eye. In variousembodiments, the increased contrast sensitivity in the sagittal planecan come at the expense of decreased visual acuity in the tangentialplane and vice versa. The various embodiments, the IOL configured toprovide increased visual acuity in the sagittal and tangential planescan include a single ring microstructure as discussed above. In variousembodiments, the IOL configured to provide increased contrastsensitivity in the sagittal and tangential planes can also provideincreased visual acuity at near or far distances. Without any loss ofgenerality, the tangential plane is the plane that contains theprincipal ray and the optical axis of the IOL and the sagittal plane isthe plane that contains only the principal ray and is orientedperpendicular to the tangential plane.

One approach to optimize the visual image in the sagittal/tangentialplanes is to implant an IOL at a first distance from the pupil in afirst eye and implant an IOL at a second distance from the pupil in asecond eye. The first and second distance can be different. For example,in various embodiments, a difference between the first and seconddistance can be approximately 0.5 mm to approximately 10 mm.

FIG. 24A is a graph illustrating MTF as a function of eccentricity forsagittal and tangential vision for an implementation of an IOL implantedat a first distance from the pupil in a first eye such that incidentlight is focused at a first axial focus position. FIG. 24B is a graphillustrating MTF as a function of eccentricity for sagittal andtangential vision for an implementation of the IOL implanted at a seconddistance from the pupil in a second eye such that incident light isfocused at a second axial focus position. The second distance is about 2mm further from the pupil as compared to the first distance. As notedfrom FIG. 24A, for the IOL implanted at the first distance, the sagittalvision (represented by solid line) has almost uniform visual acuity atdifferent values of eccentricity from about 0 to about 30 degrees.However, the visual acuity for tangential vision (represented by dashedline) decreases sharply as the eccentricity increases from about 0 toabout 30 degrees for the IOL implanted at the first distance.

It is noted from FIG. 24B that optical quality for tangential vision(represented by dashed line) for the IOL implanted at the seconddistance is better than the optical quality for tangential vision(represented by dashed line) for the IOL implanted at the first distancefor higher values of eccentricity. It is further noted from FIG. 24Bthat optical quality for sagittal vision (represented by solid line) forthe IOL implanted at the second distance is lower than the opticalquality for sagittal vision (represented by solid line) for the IOLimplanted at the first distance for higher values of eccentricity.Accordingly, due to binocular summation, the combined image produced bythe two IOLs implanted at different distances will give better visionfor both tangential and sagittal vision as compared to two IOLsimplanted at the same distance.

In various embodiments, other parameters of the IOLs such as coma,radius of curvature, focal length, etc. can be optimized separatelymonocularly such that visual acuity in the periphery for the imageproduced by combining information from each eye by employing binocularsummation can be increased. A binocular visual simulator can be used tooptimized different parameters of the IOLs such as coma, radius ofcurvature, focal length, implant distance, etc. for each eye of apatient to obtain increased visual acuity in the entire binocular fieldof view that includes the central visual zone and the peripheral visualzone. In some embodiments, the stop-shift equations and associatedmethods described herein can be used to improve or optimize theindividual IOLs in the binocular system, where each side is improved oroptimized to achieve an appropriate performance standard (e.g., byreducing peripheral aberrations along an appropriate direction).

IOL that Provides Astigmatic Correction to Improve Peripheral Vision

The field of view can be vertically divided into a first verticalhemi-field that is oriented nasally (referred to as nasal field of view)and a second vertical hemi-field oriented temporally (referred to astemporal field of view). The field of view can be horizontally dividedinto an upper horizontal hemi-field oriented upwards towards the brow(referred to as superior field of view) and a lower horizontalhemi-field oriented downwards towards the cheek (referred to as inferiorfield of view). The nasal and temporal fields of view correspond to aview along the horizontal direction while the superior and inferiorfields of view correspond to a view along the vertical direction. FIG.25 is a graph illustrating contrast sensitivity function (CSF) in thenasal, temporal, superior and inferior fields of view. The CSF valuesplotted in the graph are corrected for optical errors using an adaptiveoptics system. Thus, the CSF values depend only on the neural limits.Curve 2505 depicts the CSF 20 degrees in the periphery of the nasalfield of view. Curve 2505 depicts the CSF 20 degrees in the periphery ofthe temporal field of view. Curve 2515 depicts the CSF 20 degrees in theperiphery of the inferior field of view. Curve 2520 depicts the CSF 20degrees in the periphery of the superior field of view. It is noted fromFIG. 25 that the CSF values 20 degrees in the periphery of the nasal andtemporal fields of view are larger than the CSF values 20 degrees in theperiphery of the inferior and superior fields of view. This indicatesthat the vision is less limited by neural factors along the horizontaldirection corresponding to the nasal and temporal fields of view thanalong the vertical direction corresponding to inferior and superiorfields of view. Thus, providing optical correction along the horizontaldirection may be more advantageous than providing optical correctionalong the vertical direction.

In various embodiments, optical correction along the horizontaldirection can be provided by implanting an IOL with a toric component.In various embodiments, the toric component can be included even whenthe patient has good central vision and does not need an astigmatic ortoric correction and. The IOL with the toric component has a higheroptical power along the vertical axis corresponding to an axis of90-degrees using the common negative cylinder sign convention than thehorizontal axis corresponding to an axis of 180-degrees using the commonnegative cylinder sign convention. Such a lens can improve image qualityin the horizontal field of view. This can be beneficial to patients, asmost relevant visual tasks are carried out in the horizontal field ofview.

Additionally, the IOL can be configured to provide an astigmaticcorrection along the vertical and/or the horizontal axis. An astigmaticcorrection when combined with the correct higher order aberrations canprovide a good on-axis depth of focus, which can advantageously reducethe need for glasses to improve near distance vision. For example, asdiscussed above, vision is less limited by neural factors in thehorizontal direction, thus providing optical correction along thehorizontal direction is beneficial as compared to providing opticalcorrection along the vertical direction.

Moreover, for most daily activities peripheral vision along thehorizontal direction is more common and relevant than peripheral visionalong the vertical direction. For example, when driving the objects inthe peripheral vision along the vertical direction includes portions ofthe sky and the interior of the car which are relatively less importantto monitor as compared to objects in the peripheral vision along thehorizontal direction which include portions of the street, streetlights, incoming traffic, traffic signs, pedestrians, etc. To drivesafely, objects in the peripheral vision along the horizontal directionshould be monitored, detected, identified and resolved with sufficientacuity. Thus providing optical correction that improves visual acuityfor objects in the peripheral vision along the horizontal direction canbe beneficial for accomplishing most daily activities.

In various embodiments, the optical correction provided to increasevisual acuity along the horizontal direction can include a refractiveIOL configured such that a part of an anterior or posterior surface ofthe IOL is a toric surface and a part of the same anterior or posteriorsurface of the IOL is a non-toric surface. In various embodiments, thenon-toric part of the IOL can be a spherical surface or an asphericsurface. The toric surface can provide astigmatic correction. In variousembodiments, the toric surface can have higher optical power along thevertical axis than the horizontal axis. The view through such an IOL canincrease the contrast sensitivity along the horizontal field of view toa larger extent than the contrast sensitivity along the vertical fieldof view.

In various embodiments, the toric surface of the IOL can be configuredto provide a single add power. In some embodiments, the toric surface ofthe IOL can be configured to provide multiple add powers. In variousembodiments, the IOL can include more than one toric surface. In variousembodiments, one or more toric surface of the IOL can either besectorial or concentric.

In various embodiments, the contrast sensitivity of the field of viewcan be optimized by selecting the add power provided by the toricsurface and the position and/or orientation of the toric surface tosatisfy the individual needs of the patient. For example, a patient whodesires a good image quality indoors could be provided with an IOL thatincludes the non-toric portions in the center of the IOL and toricportions toward the edges of the IOL. Another patient may desire to haveincreased visual acuity in the peripheral vision along with increaseddepth of focus. Such patients can be provided with an IOL that includestoric portions in the center of the IOL.

The optical correction provided to increase contrast sensitivity alongthe horizontal direction can include corrections for astigmatism (e.g.,with the rule and/or against the rule astigmatism) and other sphericaland/or non-spherical aberrations (e.g., coma, trefoil, etc.). In variousembodiments, the optical correction provided to increase visual acuityalong the horizontal direction can also increase on-axis depth of focus.In various embodiments, aberrations can be included in the IOL toprovide on-axis depth of focus. The aberrations included to provideon-axis depth of focus can be a combination of spherical aberration andcoma or other higher order aberrations. In various embodiments, the IOLcan include diffractive features to extend depth of focus. In variousembodiments, one eye can be implanted with an IOL having a first amountof astigmatic correction and a first amount of aberrations and thesecond eye can be implanted with an IOL having a second amount ofastigmatic correction and a second amount of aberrations such thatincreased visual acuity for peripheral vision and increased depth offocus is obtained due to binocular summation.

IOLs that Compensate for Peripheral Refractive Errors

FIG. 26 illustrates a comparison of the cylinder in the periphery ofphakic (having a natural lens) eyes (represented by curve 2603) andpseudophakic (implanted with an IOL) eyes (represented by curve 2605).The data represented by curves 2603 and 2605 were obtained using ascanning aberrometer on 12 subjects in the age group between 64 and 80years in phakic and pseudophakic eyes with a pupil size of 3 mm. UsingCurves 2603 and 2605 are reproduced from the article “Comparison of theOptical Image Quality in the Periphery of Phakic and Pseudophakic Eyes,”by Bart Jaeken, Sandra Mirabet, Jose Maria Marin and Pablo Artal thatwas published in the journal Investigative Ophthalmology & VisualScience, Vol. 54, No. 5, pages 3594-3599, May 2013. A scanningaberrometer (e.g., a Hartmann-Shack (HS) wavefront sensor) was used toobtain values for defocus (M), cylindrical power along two axes orientedat 0 degrees and 45 degrees (J₀ and J₄₅) and higher order aberrations(e.g. spherical aberrations and coma) included in curves 2603 and 2605.FIG. 26 also illustrates data obtained from 14 phakic eyes in the agegroup less than 30 years old (represented by curve 2601). The dataincludes values for defocus (M), cylindrical power along two axesoriented at 0 degrees and 45 degrees (J₀ and J₄₅) with respect to theequator of the IOL and higher order aberrations (e.g. sphericalaberrations and coma), obtained using a complete ophthalmic analysissystem (COAS). FIG. 26 illustrates the variation of the power along thecylinder axis oriented at 0 degrees with respect to the equator (J₀) asa function of the visual field. The visual field is measured in degreesand varies between about ±40 degrees as a patient's gaze shifts fromtemporal vision to nasal vision along the natural convergence path. Theterms visual field angle and eccentricity can be used interchangeably inthe context of this application.

Comparison of curves 2601 and 2603 indicates a good agreement betweenthe COAS and the scanning aberrometer systems. Comparison of curves 2601and 2603 further indicates that the cylinder power is independent ofage. It is also observed from FIG. 26 that the cylindrical powercomponent J₀ increases in the temporal and nasal peripheral visions inpseudophakic eyes as compared with phakic eyes indicating a possibleincrease in peripheral refractive errors in patients implanted withIOLs. This increase in peripheral refractive errors can have ameasurable impact on visual function and could affect day-to-day taskssuch as driving, locomotion, gist recognition etc. Various systems andmethods to improve peripheral vision disclosed herein are based on therecognition that certain peripheral aberrations can depend not only onthe visual field angle but also on the foveal refractive correction andtherefore in the IOL power. Thus, it would be advantageous ifembodiments of IOLs take into account the effect of refractive power ofthe IOL on peripheral vision and optimize the refractive characteristicsin the periphery of the IOL accordingly.

Recent data indicates that peripheral astigmatism and/or horizontal comacan be patient independent. For example, peripheral astigmatism and/orhorizontal coma can be independent of the age of the patient and on itsgeometrical and optical properties. FIG. 27 is a graph illustrating thevariation of cylinder power along the axis oriented at 0-degrees withrespect to the equator (J₀) as a function of visual field for youngsubjects with different visual conditions (e.g., emmetropia, low myopia,moderate myopia and high myopia). Curve 2701 illustrates the variationof J₀ with visual field angle for an eye in an emmetropic state. Withoutany loss of generality, an eye in an emmetropic state has a fovealspherical equivalent power between about −0.5 Diopter and about +0.5Diopter. Curve 2703 illustrates the variation of J₀ with visual fieldangle for patients with low amounts of myopia. Without any loss ofgenerality, patients with low amounts of myopia have a foveal sphericalequivalent power between about −0.5 Diopter and about −1.5 Diopter.Curve 2705 illustrates the variation of J₀ with visual field angle forpatients suffering from moderate amounts of myopia. Without any loss ofgenerality, patients with moderate amounts of myopia have a fovealspherical equivalent power between about −1.5 Diopter and about −2.5Diopter. Curve 2707 illustrates the variation of J₀ with visual fieldangle for patients suffering from high amounts of myopia. Without anyloss of generality, patients with high amounts of myopia have a fovealspherical equivalent power between about −2.5 Diopter and −6.0 Diopter.It is noted from FIG. 27 that there is no significant difference incylinder power J₀ for an emmetropic eye and patients with low, moderateand high amounts of myopia. It is further noted from FIG. 27 thatcylinder power J₀ varies with visual field angle for the differentgroups of patients with increased astigmatism in the peripheral regions(e.g., at visual field angles with absolute value greater than about 10degrees) as compared to the central region (e.g., at visual field anglesbetween −10 degrees and +10 degrees).

Recent studies indicate that the amount of peripheral astigmatism isapproximately the same for emmetropes, hypertoropes, low myopes,moderate myopes and high myopes. Thus, peripheral astigmatism can beconsidered to be independent of the foveal refractive state of thepatient. Accordingly, the optical refractive characteristics of an IOLthat is configured to correct for peripheral astigmatism can bedetermined without taking the foveal refractive state of the patient'seye. For example, in various embodiments of the IOL, the opticalrefractive characteristics of an IOL that is configured to correct forperipheral astigmatism can be determined by considering only the obliqueincidence of light without taking into consideration any other ocularcharacteristics of the patient, such as for example, foveal refractivedata, axial length of the eye, curvature of the cornea, etc.

As discussed above and noted from FIG. 27 , the cylinder power variesnonlinearly with visual field angle. This nonlinear variation of thecylinder power with visual field angle can be quadratic with highermagnitude of cylindrical power in the peripheral regions (e.g., atvisual field angles having an absolute value greater than or equal to 10degrees) as compared to the central region (e.g., at visual field anglesbetween −10 degrees and +10 degrees). In FIG. 27 , the variation of thecylinder power decreases from a lower cylinder power in the centralregion, such as, for example, within a visual field angle of about ±10degrees to a higher negative cylinder power in the peripheral regions,such as, for example, at visual field angle greater than or equal toabout +10 degrees and/or less than or equal to −10 degrees. Accordingly,an IOL that is configured to correct for peripheral astigmatism can havean optical power distribution that varies inversely with the variationof the cylinder power such that the combination of the eye and the IOLreduces peripheral astigmatism. For example, the cylinder power of anIOL that compensates for peripheral astigmatism can increase nonlinearlyfrom a lower cylinder power in the central region to a higher positivecylinder power in the peripheral regions such that the combination ofthe eye and the IOL has negligible astigmatic power in the peripheralregions. Various embodiments of the IOL can be configured to provideperipheral astigmatic correction at all visual field angles. Someembodiments of the IOL can be configured to provide astigmaticcorrection at certain specific visual field angles (e.g., ±15 degrees,±20 degrees, ±25 degrees, ±30 degrees). An IOL configured to correct forperipheral astigmatism can include an arrangement of optical features(e.g. optical elements, grooves, volume or surface diffractive features,regions of varying refractive index, regions of varying curvatures,etc.) that results in the peripheral astigmatism having a desireddependence on eccentricity or field of view. Other methods ofcompensating peripheral astigmatism discussed above (such as correctingperipheral astigmatism using IOLs different shape factors, lensdisplacement or binocular summation) can be used simultaneously withdesigning an IOL having a cylinder power that varies nonlinearly withvisual field angle (e.g., quadratic as discussed herein).

Another peripheral aberration that can be compensated to improveperipheral vision is horizontal coma. Recent studies indicate thatsimilar to peripheral astigmatism, horizontal coma is also independentof the patient's ocular data, such as, for example, foveal refractivestate, axial length of the cornea, corneal curvature, etc. FIG. 28 is agraph illustrating the variation of horizontal coma as a function ofvisual field. It is observed from FIG. 28 that horizontal coma increaseslinearly from a negative value at a visual field angle of about −30degrees to a positive value at a visual field angle of about +30degrees. Accordingly, an IOL configured to compensate for horizontalcoma can have a horizontal coma that decreases linearly from a positivevalue at a visual field angle of about −30 degrees to a negative valueat a visual field angle of about +30 degrees such that a combination ofthe eye and the IOL has negligible horizontal coma in the peripheralregions. Various embodiments of the IOL can be configured to compensatefor horizontal coma at all visual field angles. Alternately, someembodiments of the IOL can be configured to compensate for horizontalcoma at certain specific visual field angles (e.g., ±15 degrees, ±20degrees, ±25 degrees, ±30 degrees). An IOL configured to correct forhorizontal coma can include an arrangement of optical features (e.g.optical elements, grooves, volume or surface diffractive features,regions of varying refractive index, etc.) that results in thehorizontal coma having a desired dependence on eccentricity or field ofview. Other methods of compensating horizontal coma discussed above(such as correcting horizontal using IOLs different shape factors, lensdisplacement, etc.) can be used simultaneously with designing an IOLhaving a horizontal coma that varies linearly (e.g., decreases linearly)with visual field angle. It is advantageous to consider binocular mirrorsymmetry in higher order aberrations in IOLs configured to correct coma.For example, due to binocular mirror symmetry, horizontal coma in rightand left eye have same magnitude but opposite sign. Thus, for the righteye, horizontal coma increases from negative values in the nasalperipheral region to positive values in the temporal peripheral regionand for the left eye, horizontal coma increases from negative values inthe temporal peripheral region to positive values in the nasalperipheral region. Accordingly, embodiments of IOL configured to correcthorizontal coma can be designed by adopting appropriate sign conventionsfor right and left eye. Alternately, embodiments of IOL configured tocorrect horizontal coma can include markings that indicate theorientation for placement in right and left eyes.

Another peripheral aberration that can be compensated to improveperipheral vision is defocus. Unlike peripheral astigmatism and coma,peripheral defocus depends on the foveal refractive state of thepatient. The effect of foveal refractive state on peripheral defocus isshown in FIG. 29 which illustrates the variation of defocus as afunction of visual field angle for patients with different fovealrefractive state (e.g., emmetropic eye, low myopia, moderate myopia andhigh myopia). Referring to FIG. 29 , curve 2901 shows the variation ofdefocus versus visual field angle for an emmetropic eye as measured byCOAS. In FIG. 29 , curve 2903 shows the variation of defocus versusvisual field angle for patients with low amount of myopia as measured byCOAS. In FIG. 29 , curve 2905 shows the variation of defocus versusvisual field angle for patients with moderate amount of myopia asmeasured by COAS. In FIG. 29 , curve 2907 shows the variation ofspherical optical power versus visual field angle for patients with highamount of myopia as measured by COAS.

As noted from FIG. 29 , peripheral defocus changes from a relativemyopic shift characterized by higher negative optical power in theperipheral regions (e.g., at visual field angles having an absolutevalue greater than 10 degrees) as compared to the central region (e.g.,at visual field angles between −10 degrees and +10 degrees) for anemmetropic eye or patients with low amount of myopia to a relativehyperopic shift characterized by lower negative optical power in theperipheral regions as compared to the central region for patients withmoderate to high amounts of myopia. Accordingly, an IOL configured tocompensate for peripheral defocus can have a greater amount of opticalpower in the peripheral regions as compared to the amount of opticalpower in the central region for an emmetropic eye or patients with lowmyopia and a smaller amount of optical power in the peripheral regionsas compared to the optical power in the central region for patients withmoderate to high myopia.

Various embodiments of an IOL configured to compensate for peripheraldefocus in an emmetropic eye or patients with low amount of myopia canhave a defocus power distribution that increases nonlinearly from thecentral region to the peripheral regions. In various embodiments, theoptical power distribution can be symmetric about the central regionsuch that the defocus power distribution for various embodiments of anIOL configured to compensate for peripheral defocus in an emmetropic eyeor in patients with low amount of myopia is an increasing parabola.Various embodiments of an IOL configured to compensate for peripheraldefocus in patients with moderate to high amount of myopia can have adefocus power distribution that decreases nonlinearly from the centralregion to the peripheral regions. In various embodiments, the defocuspower distribution can be symmetric about the central region such thatthe defocus power distribution for various embodiments of an IOLconfigured to compensate for peripheral defocus in patients withmoderate to high amount of myopia is a decreasing parabola.

In various implementations, the optical power distribution that cancorrect peripheral aberrations (e.g., astigmatism, coma, defocus, etc.)can depend on the refractive power of the IOL. In various embodiments,the refractive power of the IOL can be spherical and/or cylindricalpower that can achieve emmetropia, Thus, patients with high myopia canbenefit from low IOL powers while emmetropes can benefit from opticalpowers around 20-24D and patients with hyperopia can benefit from highcylinder powers. Therefore, the optical power distribution that canreduce peripheral defocus can depend on the refractive power of the IOL.An example embodiment of an IOL configured to compensate for peripheraldefocus in an emmetropic eye (e.g., an eye with spherical equivalenterror between about −0.5 Diopter and about +0.5 Diopter) having aperipheral defocus power distribution similar to the distributionillustrated by curve 2901 has an optical defocus between about −0.1-+1.0Diopter at visual field angles between about +10 degrees to +30 degreesand/or between about −10 degrees to −30 degrees. Another exampleembodiment of an IOL configured to compensate for peripheral defocus inpatients with low myopia (e.g., with spherical equivalent power betweenabout −0.5 Diopter and about −1.5 Diopter) having a defocus powerdistribution similar to the distribution illustrated by curve 2903 hasan optical defocus between about −0.1-+2.0 Diopter at visual fieldangles between about +10 degrees to +30 degrees and/or between about −10degrees to −30 degrees. Yet another example embodiment of an IOLconfigured to compensate for peripheral defocus in patients withmoderate myopia (e.g., with spherical equivalent power between about−1.5 Diopter and about −2.5 Diopter) having a defocus power distributionsimilar to the distribution illustrated by curve 2905 has an opticaldefocus between about +1.0-+3.0 Diopter at visual field angles betweenabout +10 degrees to +30 degrees and/or between about −10 degrees to −30degrees. Another example embodiment of an IOL configured to compensatefor peripheral defocus in patients with high myopia (e.g., withspherical equivalent power between about −2.5 Diopter and about −6.0Diopter) having a defocus power distribution similar to the distributionillustrated by curve 2907 has an optical defocus between about +2.5-+6.0Diopter at visual field angles between about +10 degrees to +30 degreesand/or between about −10 degrees to −30 degrees. Various embodiments ofthe IOL can be configured to compensate for defocus at all visual fieldangles. Alternately, some embodiments of the IOL can be configured tocompensate for defocus at certain specific visual field angles (e.g.,±15 degrees, ±20 degrees, ±25 degrees, ±30 degrees). Other methods ofcompensating peripheral defocus discussed above (such as correctinghorizontal using IOLs different shape factors, lens displacement, etc.)can be used simultaneously with designing an IOL having a defocus powerdistribution that is based on the foveal refractive state of thepatient.

Because peripheral defocus is related to axial length and corneal power,and these parameters are the basic input for IOL power determination,the IOL designs to correct peripheral defocus also depends on the IOLspherical power to achieve emmetropia. Emmetropes (e.g., eyes withspherical equivalent error between about +0.5 Diopter and about −0.5Diopter) have IOL powers around 20-24D. Therefore, previous embodimentsto correct peripheral defocus in emmetropes can be extended to lens withIOL powers around 20-24D. Myopes require lower IOL powers thanemmetropes (the higher the myopic error, the lower the IOL power) andhyperopes require higher IOL powers than emmetropes (the higher thehyperopic error, the higher the IOL power). Therefore, IOL designsdescribed herein to correct peripheral defocus can depend on thespherical power of the IOL.

Metrics for Evaluating the Peripheral Image Quality of IOLs

Various implementations of IOLs described herein can improve peripheralimage quality by correcting for peripheral errors. One method ofdesigning implementations of IOLs that can improve peripheral imagequality includes optimizing the image quality at multiple regions of theretina such as, for example, the fovea, and additional points in theregion of the retina surrounding the fovea. While, it may be possible tooptimize the image quality at every point of the central and peripheralvisual field, this approach may be time intensive and/or computationallyintensive. Accordingly, it is conceived that algorithms that determinethe image quality at fewer points along the retina are employed todesign implementations of IOLs that can improve peripheral image qualitywithout degrading foveal image quality. Different metrics can be used toevaluate the peripheral image quality of various lens designs. Thepresence of large amounts of peripheral aberrations, such as coma, inthe population can render the traditional metrics that have beendeveloped to evaluate the foveal image quality of existing IOLsinsufficient to evaluate the peripheral image quality of an IOL that isconfigured to improve peripheral image quality. For example, afrequently used metric to characterize the image quality at the fovea ofexisting IOLs, the visual Strehl OTF ratio, depends on foveal neuralsensitivity which may not be suitable to evaluate peripheral imagequality.

It has been proposed to use spherical and cylindrical errors in theperipheral visual field as a metric for evaluating the opticalperformance of different peripheral optics. This approach may bereasonable for phakic eyes, although some accuracy can be gained ifhigher order aberrations are included as well. However, when modelinglens designs that can improve peripheral image quality, metrics based ononly spherical and/or cylindrical errors or single aberrationcoefficients can be inadequate. This is explained with reference toFIGS. 30A-30C which illustrate the through-focus MTF curves for threelens designs evaluated at 25 degrees eccentricity in green light at 10cycles/mm. All the three lens designs have a spherical error of 0. Thefirst lens design whose performance is illustrated in FIG. 30A has acylindrical (or astigmatic) error J0=8.4 Diopters. The peak MTF fortangential rays focused by the first lens design is about 0.78 and thepeak MTF for sagittal rays focused by the first lens design is about0.7. The second lens design whose performance is illustrated in FIG. 30Bhas a cylindrical (or astigmatic) error J0=1.2 Diopter. The peak MTF fortangential rays focused by the second lens design is about 0.55 and thepeak MTF for sagittal rays focused by the first lens design is about0.8. The third lens design whose performance is illustrated in FIG. 30Chas a cylindrical (or astigmatic) error J0=0.75 Diopter. The peak MTFfor tangential rays focused by the third lens design is about 0.35 andthe peak MTF for sagittal rays focused by the first lens design is about0.4. It is observed from the MTF curves that while the astigmatic errorfor the third lens design is the lowest of the three lens designs, thepeak MTF values for tangential rays and sagittal rays focused by thethird lens design are lower than the peak MTF values for the first andthe second lens. Thus, if only the refractive and cylindrical errorswere considered to evaluate the different lens designs, then the thirdlens design would be selected over the first and second lens designs,even though the image quality provided the first and second lens designsat the peripheral retinal location is better than the third lens design.Therefore, it can advantageous to develop a new metric that can evaluatethe image quality provided by different lens designs at the peripheralretinal location.

This disclosure contemplates utilizing a metric based on the ModulationTransfer Function (MTF) to evaluate the peripheral image quality fordifferent lens designs that are configured to improve peripheral imagequality. An example of a metric to evaluate the peripheral image qualitycan be a weighted average of MTF values at different spatial frequenciesand at different eccentricities. Another example of a metric to evaluatethe peripheral image quality can be an area under the through focus MTFcurve obtained for multiple spatial frequencies and differenteccentricities.

The metrics described herein can be obtained from pre-clinicalmeasurements of an IOL design performed by a bench-top optical system orby performing simulations using an eye model. The metrics can be used topredict visual performance at different eccentricities for a range ofspatial frequencies. For example, the metrics discussed herein canpredict the image quality of a lens design when implanted in the eye fordifferent eccentricities (e.g. 5 degrees, 10 degrees, 15 degrees, 20degrees, 25 degrees, 30 degrees, or values therebetween) and a for arange of spatial frequencies between about 0 cycles per mm and about 50cycles per mm, or about 0 cycles per mm and about 100 cycles per mm, orabout 0 cycles per mm and about 200 cycles per mm.

The metrics described herein can be used to rank the visual performanceof different lens designs and thus can be used to select lenses thatwould provide optical performance that would best suit the needs of apatient when implanted in the eye of the patient. The metrics describedherein can also be used to preform pre-clinical assessment of safety andefficacy of new lens designs and select which among the new IOL designscan be used in clinical trials. The metrics described herein can also beused as a design tool to improve the performance of new and existingIOLs. The metrics described herein can be used for development andoptimization of monofocal lenses, enhanced monofocal lenses, extendeddepth of focus lenses, multifocal lenses, extended range of visionlenses. The metrics described herein can be used to develop newcategories of lenses.

FIG. 31 illustrates a flowchart 3100 depicting an implementation of amethod to obtain a metric (also referred to as a Figure of Merit (FoM))that can be used to evaluate the peripheral image quality provided by alens design. The method comprises identifying the visual field ofinterest as shown in block 3105. Identifying the visual field ofinterest can include, determining which part of the visual field shouldbe considered to evaluate the optical performance of a lens design. Forexample, the visual field of interest can include the foveal region aswell as the peripheral retinal region. As another example, the visualfield of interest can include only the peripheral portions of theretina. In various implementations, the visual field of interest caninclude a region having eccentricity greater than or equal to about 0degrees (corresponding to the foveal location) and less than or equal toabout 30 degrees. For example, the visual field of interest can includeregions having eccentricity greater than or equal to about 0 degrees(corresponding to the foveal location) and less than or equal to about10 degrees, greater than or equal to about 0 degrees (corresponding tothe foveal location) and less than or equal to about 15 degrees, greaterthan or equal to about 0 degrees (corresponding to the foveal location)and less than or equal to about 20 degrees, greater than or equal toabout 0 degrees (corresponding to the foveal location) and less than orequal to about 30 degrees, greater than or equal to about 5 degrees(corresponding to the foveal location) and less than or equal to about30 degrees, greater than or equal to about 10 degrees (corresponding tothe foveal location) and less than or equal to about 30 degrees, etc.Without any loss of generality, a retinal location having aneccentricity of 0 degrees can lie on a circle that is centered about thefovea and oriented such that a tangential line to the circle forms anangle of about 0-degrees with respect to the optical axis of the eye.

The method further comprises identifying the spatial frequencies ofinterest for which the MTF is to be calculated, as shown in block 3110.The spatial frequencies of interest can be between greater than or equalto 0 cycles/mm and less than or equal to 200 cycles/mm. For example, thespatial frequencies of interest can be greater than or equal to 0cycles/mm and less than or equal to 30 cycles/mm, greater than or equalto 0 cycles/mm and less than or equal to 50 cycles/mm, greater than orequal to 0 cycles/mm and less than or equal to 100 cycles/mm, greaterthan or equal to 10 cycles/mm and less than or equal to 200 cycles/mm,greater than or equal to 50 cycles/mm and less than or equal to 200cycles/mm, greater than or equal to 0 cycles/mm and less than or equalto 100 cycles/mm, etc. The MTF can be calculated for differentillumination conditions, such as, for example, illumination provided bya white light source or a green light source.

The method further comprises calculating a metric based on the MTFvalues obtained for the identified spatial frequencies within theidentified visual field of interest, as shown in block 3115. The metriccan be calculated by taking an average of the obtained MTF values. Forexample, the metric can be a weighted average of the obtained MTF valueswherein different weights are assigned to the MTF values obtained fordifferent spatial frequencies and different eccentricities.

The identification of the visual field of interest and the spatialfrequencies can be based on the ocular anatomy and functional tasks thatare desired to be improved. The functional tasks can include patterndetection, pattern recognition, luminance detection, car driving,walking, navigation, reading, tasks performed in photopic conditions,tasks performed in scotopic conditions, etc. The ocular anatomy caninclude photoreceptor density, iris structure, ganglion cell density,pupil size, shape and size of retina, etc. The metrics described hereincan be calculated for an entire population or a group of patients basedon average population statistic. Alternately, the metric can becalculated for a specific patient based on the patient's specific eyegeometry and the specific functional requirements of the patient.

Example Metric to Evaluate Peripheral Image Quality

An example of a metric that can be used to evaluate peripheral imagequality is described below. The visual field of interest is identified.As discussed above, the visual field of interest can be selected basedon the functional tasks to be performed and/or the ocular anatomy. Forthe purpose of the illustrative example, the visual field of interest isselected to be a circular region of the retina having an eccentricity upto 30 degrees. The retinal region having an eccentricity up to 30degrees is advantageous for driving. Different eccentricities can beselected for other tasks. For example, the visual field of interestselected for pattern detection and/or pattern recognition may be smallerthan 30 degrees. In the illustrative example, MTF curves can be obtainedfor eccentricities in increments of 5 degrees between 0 degrees and 30degrees. For example, MTF curves can be obtained at eccentricities of 0degrees (corresponding to the foveal region), 5 degrees, 10 degrees, 15degrees, 20 degrees, 25 degrees and 30 degrees. In otherimplementations, MTF curves can be obtained for more or lesseccentricities in the selected visual field of interest.

As discussed above, the spatial frequencies of interest can be selectedbased on the ocular anatomy and the functional tasks that are to beperformed. The ganglion cell density in the peripheral retina is lessthan the ganglion cell density in the central retina. Accordingly, thecontrast ratio of an image formed on the peripheral retina can be lowerthan the contrast ratio of an image formed on the central retina.Additionally, tasks (such as driving, walking, etc.) that can benefitfrom improved peripheral image quality can be performed at low spatialfrequencies and low contrast ratios. Thus, it may not be necessary toevaluate lens designs for higher spatial frequencies (e.g., 50cycles/mm, 100 cycles/mm or higher). Instead, it may be advantageous toevaluate lens designs for lower spatial frequencies. Since the ganglioncell density limits the maximum peripheral resolution that can beachieved if all peripheral errors and aberrations are corrected, therange of spatial frequencies can be selected using the distribution ofganglion cell density in the visual field of interest. FIG. 32illustrates the spatial frequency that is achievable based on theganglion cell density at different eccentricities. It is observed fromFIG. 32 that the ganglion cell density limits the maximum achievablespatial frequency to about 50 cycles/mm at an eccentricity of about 5degrees and to about 15 cycles/mm at an eccentricity of about 15degrees. In the illustrative example, the selected range of spatialfrequencies is from 0 cycles/mm to 20 cycles/mm. In other example, theupper limit on the range of spatial frequencies can be greater than 20cycles/mm. For example, the selected range of spatial frequencies can befrom 0 cycles/mm to 25 cycles/mm, 0 cycles/mm to 30 cycles/mm, 0cycles/mm to 35 cycles/mm, 0 cycles/mm to 40 cycles/mm, 0 cycles/mm to45 cycles/mm or 0 cycles/mm to 50 cycles/mm.

In the illustrative example, to calculate the metric MTF curves fortangential and sagittal rays are obtained at different eccentricityvalues from 5 degrees to 30 degrees in increments of 5 degrees fordifferent spatial frequencies between 0 cycles/mm and 20 cycles/mm. FIG.33 shows the MTF curve for tangential and sagittal rays at aneccentricity of 20 degrees for spatial frequencies between 0 cycles/mmand 20 cycles/mm for a lens design in green light. A metric can beobtained for each eccentricity to evaluate the image quality obtained ateach eccentricity. A metric for the entire range of eccentricities canbe obtained by averaging the metric obtained for each eccentricity.

In the illustrative example, the metric obtained at each eccentricity isbased on the MTF values for tangential and sagittal rays at a spatialfrequency of 10 cycles/mm and 20 cycles/mm. For example, the metric canbe an arithmetic average or a geometric average of the MTF values fortangential and sagittal rays at a spatial frequency of 10 cycles/mm and20 cycles/mm. As another example, the metric can be a weighted averageof the MTF values for tangential and sagittal rays at a spatialfrequency of 10 cycles/mm and 20 cycles/mm.

In other examples, the metric obtained at each eccentricity can be equalor proportional to the area under the MTF curve for all spatialfrequencies in the selected range.

For the purpose of the illustrative example, the metric for eacheccentricity is obtained by taking a geometric average of the MTF valuesfor tangential and sagittal rays at a spatial frequency of 10 cycles/mmand 20 cycles/mm. Selecting geometric average as a metric can simplifythe optimization process such that it converges toward a lens design inwhich the MTF values for both tangential and sagittal rays are above athreshold value thereby reducing the dependence of image quality on theorientation of the lens.

With reference to FIG. 33 , the metric FoM₂₀ for an eccentricity of 20degrees is given by:

${FoM_{20}} = {\sqrt[4]{0.86 \times 0.43 \times 0.55 \times 0.31} = {0.5}}$

Once the metric for each eccentricity (e.g., 5-degrees, 10-degrees,15-degrees, 20-degrees, 25-degrees and 30-degrees in the illustrativeexample) is obtained, the overall (also referred to as total) metric forthe peripheral retina can be calculated. The overall metric can be anarithmetic average a geometric average or a weighted average of themetric obtained at each eccentricity.

With reference to FIG. 33 , the overall metric FoM_(total) is given by:

${FoM_{total}} = {\sqrt[6]{FoM_{5} \times FoM_{10} \times FoM_{15} \times FoM_{20} \times FoM_{25} \times FoM_{30}} = {{0.6}4}}$

The metrics described above can be used to compare and evaluatedifferent lens designs. The foveal performance can be evaluatedseparately for each lens design. Alternately, the foveal performance canbe included in the metric directly. For example, in variousimplementations, the overall metric can be calculated by including afigure of merit at 0 degree eccentricity (FoM₀) can be obtained for oneor more spatial frequencies to include foveal performance. When includeddirectly in the metric, the foveal performance can be weighted with anappropriate factor.

In various implementations, the range of spatial frequencies can becalculated based on photoreceptor data instead of ganglion cell density.Lenses optimized based on photoreceptor data instead of ganglion celldensity can be suitable for detection tasks rather than tasks thatrequire resolution. The pupil size can vary depending on the task.Accordingly, the variation of the pupil size can be taken into accountwhen calculating the metrics to evaluate the optical performance ofdifferent lens designs. Chromatic effects can also be included into themetric. For example, transverse chromatic aberration can be larger inthe periphery retina than in the fovea. Accordingly, correction oftransverse chromatic aberration can be advantageous in improving theperipheral image quality. Other existing metrics adapted to fovealconditions can also be adapted to the peripheral conditions. Forexample, foveal metrics that take into consideration the ellipticalpupil shape and reduced neural sensitivity can also be adapted toevaluate the peripheral image quality of various lens designs.

Lens Designs for Improving Peripheral Image Quality in IOLs

This disclosure contemplates a range of lens designs that can improveperipheral image quality while maintaining foveal image quality. Thelens designs discussed herein can be applied to IOLs and other opticalsolutions (e.g., contact/spectacle lenses, laser ablation patterns,etc.). The implementations of lens designs described below include alens with a first surface and a second surface intersected by an opticalaxis. The optical axis can pass through the geometric center of the lensand joins the centers of curvature of the first and the second surface.Various implementations of lenses discussed herein that are configuredto improve peripheral image quality can be configured to be symmetricabout the optical axis. An advantage of having symmetric lenses is thatimage quality in different visual fields can substantially equal. Forexample, if a symmetric lens is configured to provide good image qualityin a left visual field, then it can also provide good image quality in aright visual field. Similarly, if a symmetric lens is configured toprovide good image quality in a visual field upward with respect to anaxis perpendicular to the optical axis, then it can also provide goodimage quality downward with respect to that axis. Another advantage ofhaving symmetric lenses is that the image quality in a region around theoptical axis is uniform. Accordingly, the image quality can beinsensitive to the orientation of the lens. This may make theimplantation process easier for the surgeon. Symmetric lenses may alsohave manufacturing advantages over the asymmetric lenses. The first andsecond surface of the implementations of lenses described herein can bespheric, aspheric, conic or any other shape. In various implementationsof the lenses, one or both surfaces can be a higher order aspheredescribed by the second, fourth, sixth, eight, tenth and 12^(th) ordercoefficients. Higher order aspheric surfaces can advantageously providea plurality of degrees of freedom when designing the lens. Havingplurality of degrees of freedom can be useful in designing lenses thatprovide sufficient image quality at the fovea as well as a peripheralretinal location.

The implementations of lenses described herein are configured to improveperipheral image quality without sacrificing foveal image quality. Theimplementations of lenses described below can be designed using theprinciples discussed above. For example, stop shift equations can beused to optimize the surfaces of the lenses based on their placement inthe eye to reduce at least one optical aberration (e.g., defocus,astigmatism, coma, etc.) at the peripheral retinal location. As anotherexample, the shape factor of the lenses described below can be optimizedto reduce degradation of visual information obtained from the peripheralretinal location. As yet another example, the principal plane of thelenses described below can be shifted by modifying the shape factor ofthe lenses and/or by axially displacing the lenses to improve imagequality at the peripheral retinal location. Additionally, theimplementations of lenses described herein are configured to improveperipheral image quality without sacrificing foveal image quality inbright light (photopic conditions) as well as dim light (scotopicconditions). The peripheral image quality of each implementation of alens is evaluated using a metric as described above, while the fovealimage quality is evaluated by MTF at a spatial frequency of 100cycles/mm in green light. Various implementations of lenses describedherein have a through-focus MTF of at least 0.5 for a spatial frequencyof 100 cycles/mm in green light for a large pupil having a diameter of 5mm as well as a small pupil having a diameter of 3 mm. The surfaceprofiles of the various lenses described below correspond to a baseoptical power of 20 Diopters.

Implementation of a Lens Currently Available in the Market Including anAspheric Surface (Standard Lens)

The peripheral image quality of an implementation of a lens currentlyavailable in the market (also referred to as a standard lens) wasevaluated using the metric discussed above as a baseline for comparingthe different optical solutions. The standard lens can be similar to astandard toric IOL (e.g., TECNIS®). The overall figure of merit given bya geometric average of figures of merit obtained at differenteccentricities between 5 degrees and 30 degrees in increments of 5degrees as discussed above for the implementation of the standard lenswas 0.40.

The implementation of the standard lens has a first surface and a secondsurface intersected by an optical axis that passes through the geometriccenter of the standard lens and joins the center of curvatures of thefirst and second surfaces. The first surface and second surface are bothconvex as noted from the surface sag profiles shown in FIGS. 34A and34B. FIG. 34A illustrates the surface sag of the first surface on whichlight from the object is incident. The first surface of the lens can bereferred to as an anterior surface which will face the cornea when thelens is implanted in the eye. FIG. 34B illustrates the surface sag ofthe second surface from which light incident on the lens exits the lens.The second surface of the lens can be referred to as a posterior surfacewhich will face the retina when the lens is implanted in the eye. Atleast one of the first or the second surface of the lens is asphericsuch that the lens is configured to enhance foveal image quality.

FIG. 34C illustrates the through-focus MTF at a spatial frequency of 100cycles/mm in green light for a 5 mm pupil, which can be used to measureof the foveal image quality. As noted from FIG. 34C, the through-focusMTF at a spatial frequency of 100 cycles/mm in green light is about 0.76indicating sufficient image quality at the fovea. Optical performance ofthe lens at different eccentricities between 0 to 30-degrees inincrements of 5 degrees can be deduced from the data provided in Table7.1 below. With reference to Table 7.1, M is the spherical defocus andJ0 is the astigmatic error. It is observed from Table 7.1 that at aneccentricity of about 30-degrees, the implementation of the standardlens has an astigmatic error of −1.89 Diopters and a spherical defocusvalue of about −1.28 Diopters.

The maximum distance between the two surfaces of the standard lens alongthe optical axis (also referred to as thickness of the standard lens)can be between 0.5 mm and 1 mm. The standard lens can be placed in thecapsular such that the distance between the pupil and the anteriorsurface of the lens is small. For example, the implementation of lensesdisclosed above can be implanted such that the distance between thepupil and the anterior surface of the lens is between 0.9 mm and 1.5 mm(e.g., 0.75 mm).

TABLE 7.1 Angle M J0 0 0 0 5 −0.05 −0.06 10 −0.18 −0.24 15 −0.39 −0.5320 −0.66 −0.92 25 −0.96 −1.38 30 −1.28 −1.89Meniscus Lens

An implementation of a meniscus lens was designed according to theconcepts discussed above to improve peripheral image quality withoutsacrificing foveal image quality. The implementation of the meniscuslens has a first surface and a second surface intersected by an opticalaxis that passes through the geometric center of the meniscus lens andjoins the center of curvatures of the first and second surfaces. FIG.35A illustrates the surface sag of the first surface on which light fromthe object is incident. The first surface of the lens can be referred toas an anterior surface which will face the cornea when the lens isimplanted in the eye. FIG. 35B illustrates the surface sag of the secondsurface from which light incident on the lens exits the lens. The secondsurface of the lens can be referred to as a posterior surface which willface the retina when the lens is implanted in the eye. The first surfaceis concave and the second surface is convex as noted from the surfacesag profiles shown in FIGS. 35A and 35B. In other words, the firstsurface and the second surface bend the same way with a vertex of thelens curving inwards from the edges of the lens. The thickness and theplacement of the meniscus lens can be similar to the thickness and theplacement of the standard lens discussed above. The meniscus lens isdesigned based on an assumption that a distance between the pupil andthe lens will, when combined with the right shape factor, substantiallydecrease the peripheral astigmatism. The overall figure of merit givenby a geometric average of figures of merit obtained at differenteccentricities between 5 degrees and 30 degrees in increments of 5degrees as discussed above for the implementation of meniscus lens was0.41.

The foveal image quality for the implementation of the meniscus lens canbe evaluated using the through-focus MTF at a spatial frequency of 100cycles/mm in green light for a 5 mm pupil, illustrated in FIG. 35C. Asnoted from FIG. 35C, the through-focus MTF at a spatial frequency of 100cycles/mm in green light is about 0.75 indicating sufficient imagequality at the fovea. Optical performance of the lens at differenteccentricities between 0 to 30-degrees in increments of 5 degrees can bededuced from the data provided in Table 7.2 below. With reference toTable 7.2, M is the spherical defocus and J0 is the astigmatic error. Itis observed from Table 7.2 that at an eccentricity of about 30-degrees,the implementation of the meniscus lens has an astigmatic error of −1.14Diopters and a spherical defocus value of about −0.31 Diopters.

TABLE 7.2 Angle M J0 0 0 0 5 0 −0.04 10 0 −0.15 15 0 −0.33 20 0.04 −0.5725 0.13 −0.84 30 0.31 −1.14

A comparison of the optical performance of the implementation of themeniscus lens and the standard lens shows that the implementation of themeniscus lens configured to improve peripheral image quality has afoveal image quality that is substantially equal to or within a marginof error of the foveal image quality of the standard lens. Additionally,the implementation of the meniscus lens has a depth of focus,represented by the full width of the through-focus MTF peak at athreshold MTF value (e.g., 0.2, 0.3, 0.4 or 0.5) that is substantiallyequal to or within a margin of error of the depth of focus provided bythe standard lens. Spherical defocus (M) and the astigmatic error (J0)provided by the implementation of the meniscus lens is lower than thespherical defocus (M) and the astigmatic error (J0) provided by thestandard lens. Accordingly, the implementation of the meniscus lens canreduce peripheral refraction errors without degrading the foveal imagequality. Various physical and optical characteristics of the meniscuslens described herein can be similar to the physical and opticalcharacteristics of the various lenses that are configured to focusobliquely incident light at a peripheral retinal location as describedin U.S. application Ser. No. 14/644,101 filed on Mar. 10, 2015, titled‘Dual-Optic Intraocular Lens that Improves Overall Vision where there isa Local Loss of Retinal Function;” U.S. application Ser. No. 14/644,110filed on Mar. 10, 2015, titled ‘Enhanced Toric Lens that ImprovesOverall Vision where there is a Local Loss of Retinal Function;” U.S.application Ser. No. 14/644,107 filed on Mar. 10, 2015, titled‘Piggyback Intraocular Lens that Improves Overall Vision where there isa Local Loss of Retinal Function;” and U.S. application Ser. No.14/644,082 filed on Mar. 10, 2015, titled ‘Intraocular Lens thatImproves Overall Vision where there is a Local Loss of RetinalFunction.” Each of the above-identified application is herebyincorporated by reference herein in its entirety for all that itdiscloses and is made a part of this application.

Double Aspheric Lens

An implementation of a double aspheric lens was designed according tothe concepts discussed above to improve peripheral image quality withoutsacrificing foveal image quality. The implementation of the doubleaspheric lens has a first surface and a second surface intersected by anoptical axis that passes through the geometric center of the doubleaspheric lens and joins the center of curvatures of the first and secondsurfaces. FIG. 36A illustrates the surface sag of the first surface onwhich light from the object is incident. The first surface of the lenscan be referred to as an anterior surface which will face the corneawhen the lens is implanted in the eye. FIG. 36B illustrates the surfacesag of the second surface from which light incident on the lens exitsthe lens. The second surface of the lens can be referred to as aposterior surface which will face the retina when the lens is implantedin the eye. Both the first and the second surface are higher orderaspheric surfaces including upto twelfth (12^(th)) order aspheric terms.For example, the first surface and/or the second surface can bedescribed mathematically by the equation below:

$z = {\frac{cr^{2}}{1 + \sqrt{1 - {\left( {1 + k} \right)c^{2}r^{2}}}} + {\sum\limits_{i = 1}^{6}{\alpha_{i}r^{2i}}}}$

where z is the sag of the surface, c is the curvature of the surface, rthe radial distance from the optical axis, k the conic constant and α₁,. . . , α₁₂, are the aspheric coefficients. Without any loss ofgenerality, the curvature of the surface can be correlated to theinverse of the radius of curvature R. The surface described by the aboveequation is symmetric about the optical axis and thus does not have anyangular dependency. Accordingly, the optical effect (and/or imagequality) is independent of angular location.

The values of the surface parameters such as radius of curvature,aspheric coefficients, conic constant, etc. can be different for thefirst and the second surface. For example, the surface that faces thecornea can have a high conic constant (e.g., between 10 and 1000) andthe surface that faces the retina can have a low conic constant (e.g.,between 0 and 10). The curvature of the second surface can be greaterthan or lesser than the curvature of the first surface. In theparticular implementation described herein, other parameters of the lens(e.g., thickness and placement) are similar to the standard lens.

The foveal image quality for the implementation of the double asphericlens can be evaluated using the through-focus MTF at a spatial frequencyof 100 cycles/mm in green light for a 5 mm pupil, illustrated in FIG.36C. As noted from FIG. 36C, the through-focus MTF at a spatialfrequency of 100 cycles/mm in green light is about 0.74 indicatingsufficient image quality at the fovea. Optical performance of the doubleaspheric lens at different eccentricities between 0 to 30-degrees inincrements of 5 degrees can be deduced from the data provided in Table7.3 below. With reference to Table 7.3, M is the spherical defocus andJ0 is the astigmatic error. It is observed from Table 7.3 that at aneccentricity of about 30-degrees, the implementation of the doubleaspheric lens has an astigmatic error of −1.39 Diopters and a sphericaldefocus value of about −0.27 Diopters. The overall figure of merit givenby a geometric average of figures of merit obtained at differenteccentricities between 5 degrees and 30 degrees in increments of 5degrees as discussed above for the implementation of double asphericlens was 0.50 corresponding to an average contrast ratio increase ofabout 25% as compared to the standard lens.

TABLE 7.3 Angle M J0 0 −0.02 0 5 −0.04 −0.05 10 −0.09 −0.19 15 −0.17−0.41 20 −0.24 −0.70 25 −0.28 −1.04 30 −0.27 −1.39

A comparison of the optical performance of the implementation of thedouble aspheric lens and the standard lens shows that the implementationof the double aspheric lens configured to improve peripheral imagequality has a foveal image quality that is substantially equal to orwithin a margin of error of the foveal image quality of the standardlens. Additionally, the implementation of the double aspheric lens has adepth of focus, represented by the full width of the through-focus MTFpeak at a threshold MTF value (e.g., 0.2, 0.3, 0.4 or 0.5) that issubstantially equal to or within a margin of error of the depth of focusprovided by the standard lens. Spherical defocus (M) and the astigmaticerror (J0) provided by the implementation of the double aspheric lens islower than the spherical defocus (M) and the astigmatic error (J0)provided by the standard lens. Additionally, the implementation of thedouble aspheric lens provides about 25% increase in the contrast ratioas compared to the standard lens. Accordingly, the implementation of thedouble aspheric lens can reduce peripheral refraction errors and improveperipheral image quality without degrading the foveal image quality.Various physical and optical characteristics of the double aspheric lensdescribed herein can be similar to the physical and opticalcharacteristics of the various lenses that are configured to focusobliquely incident light at a peripheral retinal location as describedin U.S. application Ser. No. 14/644,101 filed on Mar. 10, 2015, titled‘Dual-Optic Intraocular Lens that Improves Overall Vision where there isa Local Loss of Retinal Function;” U.S. application Ser. No. 14/644,110filed on Mar. 10, 2015, titled ‘Enhanced Toric Lens that ImprovesOverall Vision where there is a Local Loss of Retinal Function;” U.S.application Ser. No. 14/644,107 filed on Mar. 10, 2015, titled‘Piggyback Intraocular Lens that Improves Overall Vision where there isa Local Loss of Retinal Function;” and U.S. application Ser. No.14/644,082 filed on Mar. 10, 2015, titled ‘Intraocular Lens thatImproves Overall Vision where there is a Local Loss of RetinalFunction.” Each of the above-identified application is herebyincorporated by reference herein in its entirety for all that itdiscloses and is made a part of this application.

Thick Lens

An implementation of a thick lens was designed according to the conceptsdiscussed above to improve peripheral image quality without sacrificingfoveal image quality. The implementation of the thick lens has a firstsurface and a second surface intersected by an optical axis that passesthrough the geometric center of the thick lens and joins the center ofcurvatures of the first and second surfaces. FIG. 37A illustrates thesurface sag of the first surface on which light from the object isincident. The first surface of the lens can be referred to as ananterior surface which will face the cornea when the lens is implantedin the eye. FIG. 37B illustrates the surface sag of the second surfacefrom which light incident on the lens exits the lens. The second surfaceof the lens can be referred to as a posterior surface which will facethe retina when the lens is implanted in the eye. Both the first and thesecond surface are higher order aspheric surfaces including upto eighth(8^(th)) order aspheric terms. In the particular implementationdescribed herein, the placement of the thick lens in the eye is similarto the standard lens. However, the thickness of the thick lens isincreased to 1.5 mm.

The foveal image quality for the implementation of the thick lens can beevaluated using the through-focus MTF at a spatial frequency of 100cycles/mm in green light for a 5 mm pupil, illustrated in FIG. 37C. Asnoted from FIG. 37C, the through-focus MTF at a spatial frequency of 100cycles/mm in green light is about 0.73 indicating sufficient imagequality at the fovea. Optical performance of the double aspheric lens atdifferent eccentricities between 0 to 30-degrees in increments of 5degrees can be deduced from the data provided in Table 7.4 below. Withreference to Table 7.4, M is the spherical defocus and J0 is theastigmatic error. It is observed from Table 7.4 that at an eccentricityof about 30-degrees, the implementation of the double aspheric lens hasan astigmatic error of −1.19 Diopters and a spherical defocus value ofabout −0.15 Diopters. The overall figure of merit given by a geometricaverage of figures of merit obtained at different eccentricities between5 degrees and 30 degrees in increments of 5 degrees as discussed abovefor the implementation of thick lens was 0.48 corresponding to anaverage contrast ratio increase of about 25% as compared to the standardlens.

TABLE 7.4 Angle M J0 0 −0.02 0 5 −0.03 −0.04 10 −0.04 −0.16 15 −0.06−0.35 20 −0.05 −0.60 25 −0.01 −0.89 30 −0.15 −1.19

A comparison of the optical performance of the implementation of thethick lens and the standard lens shows that the implementation of thethick lens configured to improve peripheral image quality has a fovealimage quality that is substantially equal to or within a margin of errorof the foveal image quality of the standard lens. Additionally, theimplementation of the thick lens has a depth of focus, represented bythe full width of the through-focus MTF peak at a threshold MTF value(e.g., 0.2, 0.3, 0.4 or 0.5) that is substantially equal to or within amargin of error of the depth of focus provided by the standard lens.Spherical defocus (M) and the astigmatic error (J0) provided by theimplementation of the thick lens is lower than the spherical defocus (M)and the astigmatic error (J0) provided by the standard lens.Additionally, the implementation of the thick lens provides about 25%increase in the contrast ratio as compared to the standard lens.Accordingly, the implementation of the thick lens can reduce peripheralrefraction errors and improve peripheral image quality without degradingthe foveal image quality.

It is further noted from a comparison of the double aspheric lens andthe thick lens that while the extra thickness of the thick lensdecreases spherical and cylindrical errors, it does not substantiallyaffect the overall figure of merit. Various physical and opticalcharacteristics of the thick lens described herein can be similar to thephysical and optical characteristics of the various lenses that areconfigured to focus obliquely incident light at a peripheral retinallocation as described in U.S. application Ser. No. 14/644,101 filed onMar. 10, 2015, titled ‘Dual-Optic Intraocular Lens that Improves OverallVision where there is a Local Loss of Retinal Function;” U.S.application Ser. No. 14/644,110 filed on Mar. 10, 2015, titled ‘EnhancedToric Lens that Improves Overall Vision where there is a Local Loss ofRetinal Function,” U.S. application Ser. No. 14/644,107 filed on Mar.10, 2015, titled ‘Piggyback Intraocular Lens that Improves OverallVision where there is a Local Loss of Retinal Function;” and U.S.application Ser. No. 14/644,082 filed on Mar. 10, 2015, titled‘Intraocular Lens that Improves Overall Vision where there is a LocalLoss of Retinal Function.” Each of the above-identified application ishereby incorporated by reference herein in its entirety for all that itdiscloses and is made a part of this application.

Shifted or (Moved) Aspheric Lens

As discussed above, the implementations of lenses discussed above can beimplanted in the eye such that the distance between the pupil and theanterior surface of the lens is small. For example, the implementationof lenses disclosed above can be implanted such that the distancebetween the pupil and the anterior surface of the lens is between 0.9 mmand 1.5 mm. However, it is also conceived that the implementations ofthe lens discussed above can be implanted as far back in the eye aspossible. For example, in some implementations, the lens can beimplanted such that it is still in the capsular bag but is closer to theretina. In such implementations, the distance between the pupil and theanterior surface of the lens can be between distance between 1.5 mm and3.2 mm. As discussed above, axially displacing the lens can modify theprincipal plane of the lens which in turn can affect the peripheralaberrations. Accordingly, parameters (e.g., the asphericity) of thevarious surfaces of an aspheric lens can change if the lens is placedcloser to the retina. The surface profiles of an aspheric lens that isplaced closer to the retina that would reduce peripheral aberrations canbe obtained using the stop-shift equations described above. The surfaceprofiles of an aspheric lens that is configured to be placed at adistance of about 2 mm from the position of the standard lens whenimplanted is shown in FIGS. 38A and 38B. The implementation of theshifted aspheric lens was designed according to the concepts discussedabove to improve peripheral image quality without sacrificing fovealimage quality. FIG. 38A illustrates the surface sag of the first surfaceon which light from the object is incident also referred to as theanterior surface and FIG. 38B illustrates the surface sag of the secondsurface from which light incident on the lens exits the lens alsoreferred to as the posterior surface. Both the first and the secondsurface are configured as higher order aspheric surfaces including uptotenth (10^(th)) order aspheric terms. In the particular implementationdescribed herein, the thickness of the aspheric lens is similar to thestandard lens. However, the aspheric lens is displaced by about 2.0 mmtowards the retina when implanted in the eye as compared to the standardlens.

The foveal image quality for the implementation of the shifted asphericlens can be evaluated using the through-focus MTF at a spatial frequencyof 100 cycles/mm in green light for a 5 mm pupil, illustrated in FIG.38C. As noted from FIG. 38C, the through-focus MTF at a spatialfrequency of 100 cycles/mm in green light is about 0.73 indicatingsufficient image quality at the fovea. Optical performance of the doubleaspheric lens at different eccentricities between 0 to 30-degrees inincrements of 5 degrees can be deduced from the data provided in Table7.5 below. With reference to Table 7.5, M is the spherical defocus andJ0 is the astigmatic error. It is observed from Table 7.5 that at aneccentricity of about 30-degrees, the implementation of the doubleaspheric lens has an astigmatic error of −1.87 Diopters and a sphericaldefocus value of about −0.75. The overall figure of merit given by ageometric average of figures of merit obtained at differenteccentricities between 5 degrees and 30 degrees in increments of 5degrees as discussed above for the implementation of shifted asphericlens was 0.56 corresponding to an average contrast ratio increase ofabout 40% as compared to the standard lens.

TABLE 7.5 Angle M J0 0 −0.01 0 5 0 −0.03 10 0.02 −0.12 15 0.06 −0.28 200.08 −0.52 25 −0.05 −0.94 30 −0.75 −1.87

A comparison of the optical performance of the implementation of thethick lens and the standard lens shows that the implementation of theshifted aspheric lens configured to improve peripheral image quality hasa foveal image quality that is substantially equal to or within a marginof error of the foveal image quality of the standard lens. Additionally,the implementation of the thick lens has a depth of focus, representedby the full width of the through-focus MTF peak at a threshold MTF value(e.g., 0.2, 0.3, 0.4 or 0.5) that is substantially equal to or within amargin of error of the depth of focus provided by the standard lens. Theshifted aspheric lens provides some reduction in the spherical defocus(M) over the standard lens but does not provide significant improvementin the astigmatic error (J0) over the standard lens. Additionally, theimplementation of the shifted aspheric lens provides about 50% increasein the contrast ratio as compared to the standard lens. Accordingly, theimplementation of the shifted aspheric lens can reduce peripheralrefraction errors and improve peripheral image quality without degradingthe foveal image quality. Various physical and optical characteristicsof the shifted aspheric lens described herein can be similar to thephysical and optical characteristics of the various lenses that areconfigured to focus obliquely incident light at a peripheral retinallocation as described in U.S. application Ser. No. 14/644,101 filed onMar. 10, 2015, titled ‘Dual-Optic Intraocular Lens that Improves OverallVision where there is a Local Loss of Retinal Function;” U.S.application Ser. No. 14/644,110 filed on Mar. 10, 2015, titled ‘EnhancedToric Lens that Improves Overall Vision where there is a Local Loss ofRetinal Function;” U.S. application Ser. No. 14/644,107 filed on Mar.10, 2015, titled ‘Piggyback Intraocular Lens that Improves OverallVision where there is a Local Loss of Retinal Function;” and U.S.application Ser. No. 14/644,082 filed on Mar. 10, 2015, titled‘Intraocular Lens that Improves Overall Vision where there is a LocalLoss of Retinal Function.” Each of the above-identified application ishereby incorporated by reference herein in its entirety for all that itdiscloses and is made a part of this application.

Dual Optic Lens

An implementation of a dual optic aspheric lens was designed accordingto the concepts discussed above to improve peripheral image qualitywithout sacrificing foveal image quality. The implementation of the dualoptic lens includes two optics that are separated from each other by adistance of 1.5 mm. The distance between the two optics of the dualoptic lens is fixed in the particular implementation described herein.Each optic of the dual optic lens has a first surface and a secondsurface intersected by an optical axis that passes through the geometriccenter of the lens and joins the center of curvatures of the first andsecond surfaces. The optical axis of each of the two optics can coincidewith each other, be tilted with respect to each other or be offset fromeach other. FIG. 39A illustrates the surface sag of the first surface ofthe first optic of the dual optic lens, the first surface of the firstoptic can be the surface on which light from the object is incident andcan be referred to as an anterior surface which will face the corneawhen the dual optic lens is implanted in the eye. FIG. 39B illustratesthe surface sag of the second surface of the first optic of the dualoptic lens from which light exits the first optic. FIG. 39C illustratesthe surface sag of the first surface of the second optic of the dualoptic lens which receives light that exits the first optic. FIG. 39Dillustrates the surface sag of the second surface of the second optic ofthe dual optic lens from which light exits the dual optic lens. Thesecond surface of the second optic can be referred to as a posteriorsurface which will face the retina when the dual optic lens is implantedin the eye. The first and the second surfaces of the first and secondoptics can be aspheric surfaces including upto eighth (8^(th)) orderaspheric terms. In the particular implementation described herein, thethickness of the first optic is 0.557 mm and the thickness of the secondoptic is 0.916 mm.

The foveal image quality for the implementation of the dual optic lenscan be evaluated using the through-focus MTF at a spatial frequency of100 cycles/mm in green light for a 5 mm pupil, illustrated in FIG. 39C.As noted from FIG. 39C, the through-focus MTF at a spatial frequency of100 cycles/mm in green light is about 0.74 indicating sufficient imagequality at the fovea. Optical performance of the dual optic lens atdifferent eccentricities between 0 to 30-degrees in increments of 5degrees can be deduced from the data provided in Table 7.6 below. Withreference to Table 7.6, M is the spherical defocus and J0 is theastigmatic error. It is observed from Table 7.6 that at an eccentricityof about 30-degrees, the implementation of the double aspheric lens hasan astigmatic error of −0.66 Diopters and a spherical defocus value ofabout −1.03 Diopters. The overall figure of merit given by a geometricaverage of figures of merit obtained at different eccentricities between5 degrees and 30 degrees in increments of 5 degrees as discussed abovefor the implementation of the dual optic lens was 0.56 corresponding toan average contrast ratio increase of about 40% as compared to thestandard lens.

TABLE 7.6 Angle M J0 0 0.01 0 5 0.05 −0.03 10 0.07 −0.10 15 0.17 −0.2220 0.33 −0.39 25 0.58 −0.55 30 1.03 −0.66

A comparison of the optical performance of the implementation of thedual optic lens and the standard lens shows that the implementation ofthe dual optic lens configured to improve peripheral image quality has afoveal image quality that is substantially equal to or within a marginof error of the foveal image quality of the standard lens. Additionally,the implementation of the dual optic lens has a depth of focus,represented by the full width of the through-focus MTF peak at athreshold MTF value (e.g., 0.2, 0.3, 0.4 or 0.5) that is substantiallyequal to or within a margin of error of the depth of focus provided bythe standard lens. Spherical defocus (M) and the astigmatic error (J0)provided by the implementation of the dual optic lens is lower than thespherical defocus (M) and the astigmatic error (J0) provided by thestandard lens. Additionally, the implementation of the dual optic lensprovides about 50% increase in the contrast ratio as compared to thestandard lens. Accordingly, the implementation of the dual optic lenscan reduce peripheral refraction errors and improve peripheral imagequality without degrading the foveal image quality. Various physical andoptical characteristics of the dual optic lens described herein can besimilar to the physical and optical characteristics of the variouslenses that are configured to focus obliquely incident light at aperipheral retinal location as described in U.S. application Ser. No.14/644,101 filed on Mar. 10, 2015 and issued as U.S. Pat. No. 9,579,192,titled ‘Dual-Optic Intraocular Lens that Improves Overall Vision wherethere is a Local Loss of Retinal Function;” U.S. application Ser. No.14/644,110 filed on Mar. 10, 2015 and issued as U.S. Pat. No. 9,636,215,titled ‘Enhanced Toric Lens that Improves Overall Vision where there isa Local Loss of Retinal Function;” U.S. application Ser. No. 14/644,107filed on Mar. 10, 2015 and issued as U.S. Pat. No. 10,136,990, titled‘Piggyback Intraocular Lens that Improves Overall Vision where there isa Local Loss of Retinal Function;” and U.S. application Ser. No.14/644,082 filed on Mar. 10, 2015 and issued as U.S. Pat. No. 9,867,693,titled ‘Intraocular Lens that Improves Overall Vision where there is aLocal Loss of Retinal Function.” Each of the above-identifiedapplication is hereby incorporated by reference herein in its entiretyfor all that it discloses and is made a part of this application.

Accommodating Dual Optic Lens

An implementation of an accommodating dual optic lens was designedaccording to the concepts discussed above to improve peripheral imagequality without sacrificing foveal image quality. Without any loss ofgenerality, an IOL that is configured to change the axial position ofthe optic and/or shape and size of the optic in response to ocularforces applied by the capsular bag and/or ciliary muscles can bereferred to as an accommodating lens. The implementation of theaccommodating dual optic lens includes two optics that are separatedfrom each other by a variable distance. The distance between the twooptics of the accommodating dual optic lens can be varied in response toocular forces exerted by the capsular bag, the zonules and/or thecillary muscles. The dual optic lens can be configured to provide uptoabout 1.0 Diopter of additional optical power when the distance betweenthe two optics is varied.

Each optic of the dual optic lens has a first surface and a secondsurface intersected by an optical axis that passes through the geometriccenter of the lens and joins the center of curvatures of the first andsecond surfaces. The optical axis of each of the two optics can coincidewith each other, be tilted with respect to each other or be offset fromeach other. In the particular implementation described herein, a firstoptic of the accommodating dual optic lens which is configured toreceive incident light from the object (also referred to as an anterioroptic) can be a spherical lens having an optical power of about 25Diopter. In the particular implementation described herein, a secondoptic of the accommodating dual optic lens from which light exits thedual optic lens (also referred to as a posterior optic) includes twoaspheric surfaces. The surfaces of the posterior optic can include uptoeighth (8^(th)) order aspheric terms. In the particular implementationdescribed herein, the thickness of the first and the second optic isabout 0.9 mm. Various physical and optical characteristics of theaccommodating dual optic lens described herein can be similar to thephysical and optical characteristics of the various lenses that areconfigured to focus obliquely incident light at a peripheral retinallocation as described in U.S. application Ser. No. 14/644,101 filed onMar. 10, 2015, titled ‘Dual-Optic Intraocular Lens that Improves OverallVision where there is a Local Loss of Retinal Function;” U.S.application Ser. No. 14/644,110 filed on Mar. 10, 2015, titled ‘EnhancedToric Lens that Improves Overall Vision where there is a Local Loss ofRetinal Function;” U.S. application Ser. No. 14/644,107 filed on Mar.10, 2015, titled ‘Piggyback Intraocular Lens that Improves OverallVision where there is a Local Loss of Retinal Function;” and U.S.application Ser. No. 14/644,082 filed on Mar. 10, 2015, titled‘Intraocular Lens that Improves Overall Vision where there is a LocalLoss of Retinal Function.” Each of the above-identified application ishereby incorporated by reference herein in its entirety for all that itdiscloses and is made a part of this application.

FIG. 40A illustrates the surface sag of the first surface of the firstoptic of the dual optic lens, the first surface of the first optic canbe the surface on which light from the object is incident and can bereferred to as an anterior surface which will face the cornea when thedual optic lens is implanted in the eye. FIG. 40B illustrates thesurface sag of the second surface of the first optic of the dual opticlens from which light exits the first optic. FIG. 40C illustrates thesurface sag of the first surface of the second optic of the dual opticlens which receives light that exits the first optic. FIG. 40Dillustrates the surface sag of the second surface of the second optic ofthe dual optic lens from which light exits the dual optic lens. Thesecond surface of the second optic can be referred to as a posteriorsurface which will face the retina when the dual optic lens is implantedin the eye.

The foveal image quality for the implementation of the accommodatingdual optic lens can be evaluated using the through-focus MTF at aspatial frequency of 100 cycles/mm in green light for a 5 mm pupil,illustrated in FIG. 40C. As noted from FIG. 40C, the through-focus MTFat a spatial frequency of 100 cycles/mm in green light is about 0.57which is lesser than the MTF of the standard lens described above.However, the MTF of the accommodating dual optic lens at a spatialfrequency of 100 cycles/mm in green light is similar to the MTF achievedby a standard spherical lens having accommodating capabilities.

Optical performance of the dual optic lens at different eccentricitiesbetween 0 to 30-degrees in increments of 5 degrees can be deduced fromthe data provided in Table 7.7 below. With reference to Table 7.7, M isthe spherical defocus and J0 is the astigmatic error. It is observedfrom Table 7.7 that at an eccentricity of about 30-degrees, theimplementation of the double aspheric lens has an astigmatic error of−13.7 Diopters and a spherical defocus value of about −21.15 Diopters.Although, the refractive errors are larger as compared to the standardlens, the overall figure of merit given by a geometric average offigures of merit obtained at different eccentricities between 5 degreesand 30 degrees in increments of 5 degrees as discussed above for theimplementation of the accommodating dual optic lens was 0.53corresponding to an average contrast ratio increase of about 40% ascompared to the standard lens.

TABLE 7.7 Angle M J0 0 −0.13 0 5 −0.29 0.12 10 −0.92 −0.56 15 −0.246−1.63 20 −5.61 −3.73 25 −11.36 −7.47 30 −21.15 −13.70Summary of Various Optical Lens Designs

The peripheral and the foveal image quality for the various lens designsdiscussed above are summarized in Tables 7.8 and 7.9 below. Table 7.8provides the summary of the optical performance for a 5 mm pupil andtable 7.9 provides the summary of the optical performance for a 3 mmpupil. As discussed above, the various lens designs represent differentoptical surface configurations that through the use of optimizationalgorithms and metrics, as described above, are configured to provideimproved peripheral image quality. From Tables 7.8 and 7.9, it is notedthat the different lens designs with the exception of the meniscus lensdesign, gives a figure of merit increase corresponding to an average MTFgain in a peripheral image between about 25%-50% as compared to thestandard lens, with the more complex designs providing a higher MTFgain. It is also noted that it is advantageous to use MTF based metricsto evaluate the peripheral image quality instead of the optical errors(e.g., spherical defocus or astigmatic error) in the peripheral image.For example, although the meniscus lens design significantly reducedoptical errors in the peripheral image as compared to the standard lens,the overall figure of merit for the meniscus lens design was equal tothe overall figure of merit of the standard lens. The lack ofimprovement in the overall MTF of the meniscus lens design can beattributed to a combination of higher order aberrations. As anotherexample, the accommodating dual optic lens had a higher overall figureof merit as compared to the standard lens despite having large opticalerrors.

TABLE 7.8 Optical Performance of Various Lens designs for 5 mm pupilOverall Figure Foveal MTF Design of merit 100 c/mm Standard lens 0.400.76 Meniscus lens 0.41 0.75 Double aspheric lens 0.50 0.74 Thick lens0.48 0.73 Shifted aspheric lens 0.56 0.72 Dual optic lens 0.56 0.74Accommodating Dual optic lens 0.53 0.57

TABLE 7.9 Optical Performance of Various Lens designs for 3 mm pupilOverall Figure Foveal MTF Design of merit 100 c/mm Standard lens 0.440.61 Meniscus lens 0.61 0.59 Double aspheric lens 0.66 0.61 Thick lens0.70 0.61 Shifted aspheric lens 0.69 0.60 Dual optic lens 0.68 0.62Accommodating Dual optic lens 0.67 0.61

A comparison of the optical performance of the different lens designs inbright conditions (pupil size of 3 mm) tabulated in Table 7.9 indicatesthat the overall figures of merits are increased for the different lensdesigns as compared to the standard lens whereas the foveal MTF remainssubstantially equal to the foveal MTF provided by the standard lens. Itis further noted that the optical performance of the thick lensthickness is comparable to the optical performance of the other lensdesigns. Furthermore, the meniscus lens has a higher overall figure ofmerit as compared to the overall figure of merit of the standard lenssince higher order aberrations introduced by the meniscus less are lessrelevant when the pupil size is small. It is also observed that thefoveal image quality of the accommodating dual optic lens is comparableto the other lens designs.

The various lens designs discussed above can be implemented in an IOLincluding an optic having surfaces similar to the surface profilesdescribed above and an haptic that holds the IOL in place when implantedin the eye. The haptic can comprise a biocompatible material that issuitable to engage the capsular bag of the eye, the iris, the sulcusand/or the ciliary muscles of the eye. For example, the haptic cancomprise materials such as acrylic, silicone, polymethylmethacrylate(PMMA), block copolymers of styrene-ethylene-butylene-styrene (C-FLEX)or other styrene-base copolymers, polyvinyl alcohol (PVA), polystyrene,polyurethanes, hydrogels, etc. In various implementations, the hapticcan include a one or more arms that are coupled to the optic of the IOL.For example, the haptic can be configured to have a structure similar tothe structure of the biasing elements disclosed in U.S. Publication No.2013/0013060 which is incorporated by reference herein in its entirety.In various implementations, the haptic can include one or more arms thatprotrude into the optic. In various implementations, the haptic can beconfigured to move the optic along the optical axis of the eye inresponse to ocular forces applied by the capsular bag and/or the ciliarymuscles. For example, the haptic can include one or more hinges tofacilitate axial movement of the optic. As another example, the hapticcan include springs or be configured to be spring-like to effectmovement of the optic. In this manner, the axial position of the opticcan be varied in response to ocular forces to provide vision over a widerange of distances. In various implementations, the haptic can also beconfigured to change a shape of the optic in response to ocular forces.As discussed above, varying the axial position of the optic or the shapeof the optic can shift the principal plane which can affect (e.g.,reduce) one or more peripheral optical aberrations. Thus, the haptic canbe configured to reduce at least one optical aberration in an imageformed at a peripheral retinal location.

The optic of the lens can be configured such that the refractiveproperties of the optic can be changed in response to the eye's naturalprocess of accommodation. For example, the optic can comprise adeformable material that can compress or expand in response to ocularforces applied by the capsular bag and/or the ciliary muscles. Asanother example, the optic can be configured to change their shape inresponse to ocular forces in the range between about 1 gram to about 10grams, 5 to 10 grams, 1 to 5 grams, about 1 to 3 grams or valuestherebetween to provide an optical power change between about 0.5Diopters and about 6.0 Diopters. In various implementations, the opticcan comprise materials such as acrylic, silicone, polymethylmethacrylate(PMMA), block copolymers of styrene-ethylene-butylene-styrene (C-FLEX)or other styrene-base copolymers, polyvinyl alcohol (PVA), polystyrenes,polyurethanes, hydrogels, etc. The optic can comprise structures andmaterials that are described in U.S. Publication No. 2013/0013060 whichis incorporated by reference herein in its entirety.

The lens designs discussed above can be configured such that lightincident on the cornea parallel to the optical axis of the eye isfocused on the central portion of the retina so as to produce afunctional foveal image having sufficient image quality. For example,the foveal image can have a MTF of at least 0.5 at a spatial frequencygreater than or equal to 50 cycles/mm in green light for a pupil size of3-5 mm. Additionally, light incident at oblique angles from is focusedat a location of the peripheral retina away from the fovea so as toproduce a functional peripheral image with sufficient image quality. Thelight can be incident obliquely from the vertical field of view or thehorizontal field of view. For example, the implementations of lensesdiscussed herein can be configured to focus light incident at obliqueangles between about 5 degrees and about 30 degrees with respect to theoptical axis of the eye, between about 10 degrees and about 25 degreeswith respect to the optical axis of the eye, between about 15 degreesand about 20 degrees with respect to the optical axis of the eye, orthere between at a location on the peripheral retina away from thefovea. Additionally, the lenses discussed herein can also be configuredto accommodate to focus objects located at different distances on to theretina (e.g., at a location on the periphery of the retina and/or thefovea) in response to ocular forces exerted by the capsular bag and/orciliary muscles. Portions of the first or second surface of the lensesdescribed above can be toric so as to provide corneal astigmaticcorrection. The first or the second surface of the lenses describedabove can include diffractive features to provide a larger depth offield. The first or the second surface of the lenses described above caninclude extra apertures to further enhance peripheral image quality. Thefirst or the second surface of the lenses described above can includeasymmetric parts to selectively improve parts of the visual field. Forexample as discussed above, the first or second surface of the lensesdescribed above can include a toric component having a higher opticalpower along the vertical axis corresponding to an axis of 90-degreesusing the common negative cylinder sign convention than the horizontalaxis corresponding to an axis of 180-degrees using the common negativecylinder sign convention. Such a lens can improve image quality in thehorizontal field of view which can be beneficial to patients, as mostrelevant visual tasks are carried out in the horizontal field of view.The various lens designs discussed above can be implemented as add-onlenses to existing IOLs to improve peripheral image quality of existingIOLs.

The implementations of lenses described in this disclosure can beconfigured to correct lower order errors (e.g. sphere and cylinder),higher order aberrations (e.g., coma, trefoil) or both resulting fromthe oblique incidence of light in the image formed at a location of theperipheral retina. The geometry of the various surfaces of the lensesdescribed in this disclosure, the thickness of the lenses described inthis disclosure, the placement of the various implementations of lensesdescribed in this disclosure and other parameters can be configured suchthat the lenses can focus light incident parallel to the optical axis atthe fovea with sufficient visual contrast and light incident at aplurality of oblique angles (e.g., between about −25 degree and about+25 degrees with respect to the optical axis of the eye) in an areaaround a location on the peripheral retina spaced away from the foveawith sufficient visual contrast. The various lens designs discussedabove can be implemented as an add-on lens to improve image quality at aperipheral location by reducing one or more optical aberrations at theperipheral location in patients who have been fitted with a standardintraocular lens currently available in the market.

Example Method of Designing an IOL to Compensate for PeripheralAberrations

An example method of designing an IOL to compensate for peripheralaberrations is illustrated in FIG. 41 . The method 3000 includesobtaining ocular measurements for a patient as shown in block 3005. Theocular measurements can be obtained using a COAS and any biometer whichis currently available in ophthalmology practice. The ocularmeasurements can include obtaining axial length of the eye, cornealpower and the spherical power that achieves emmetropia. The ocularmeasurements can include obtaining the variation of the peripheralastigmatism, horizontal coma and spherical optical power as a functionof visual field angle.

The method 3000 is configured to determine an IOL design including aplurality of optical features that compensates for peripheralastigmatism, horizontal coma and peripheral defocus as shown in theblock 3025. The plurality of optical features can include one or moreoptical elements (e.g., focusing elements, diffracting elements),grooves, volume or surface diffractive features, etc. In variousembodiments, the plurality of optical features can include regions ofvarying refractive index and/or regions with varying curvatures. Invarious embodiments, some of the plurality of optical features can bearranged regularly to form a pattern. In various embodiments, some ofthe plurality of optical features can be arranged in a random manner.The plurality of optical features can include or be based on a first setof optical features configured to compensate for peripheral astigmatismas shown in block 3010, a second set of optical features configured tocompensate for horizontal coma, as shown in block 3015 and a third setof optical features configured to compensate for peripheral defocus asshown in block 3020.

As discussed above, peripheral astigmatism is independent of thepatient's biometric inputs. Accordingly, the determination of the firstset of optical features that result in an optical power distributionthat corrects for peripheral astigmatism can be independent of thepatient's biometric inputs. In various embodiments, the arrangement ofthe first set of optical features can provide greater cylinder power inthe peripheral regions at visual field angles having an absolute valuegreater than about 10 degrees as compared to the cylinder power providedin the central region at visual field angles between about −10 degreesand about +10 degrees. In various embodiments, the arrangement of thefirst set of optical features can provide cylinder power thatcontinuously increases from the central region to the peripheral regionssuch that peripheral astigmatism is compensated at most or all visualfield angles. This variation can be nonlinear in different embodiments.For example, in various embodiments, the cylinder power resulting fromthe arrangement of the first set of optical features can increasequadratically from the central region to the peripheral regions. In someembodiments, the arrangement of the first set of optical features canprovide additional cylinder power that compensates for peripheralastigmatism only at certain specific visual field angles (e.g., ±15degrees, ±20 degrees, ±25 degrees, ±30 degrees).

As discussed above, horizontal coma is independent of the patient'sbiometric inputs. Accordingly, the determination of the second set ofoptical features that results in an optical power distribution thatcorrects for horizontal coma can be independent of the patient'sbiometric inputs. In various embodiments, the amount of horizontal comaprovided by the arrangement of the second set of optical features candecrease linearly from positive values at a visual field angle of about−40 degrees to negative values at a visual field angle of about +40degrees. In various embodiments, the arrangement of the second set ofoptical features can provide a horizontal coma value that variescontinuously (e.g., increasing for right eyes and decreasing for lefteyes) from the temporal peripheral region to the nasal temporal regionsuch that horizontal coma is compensated at most or all visual fieldangles. Alternately, in some embodiments, the IOL can be configured tocompensate for horizontal coma only at certain specific visual fieldangles (e.g., ±15 degrees, ±20 degrees, ±25 degrees, ±30 degrees).

As discussed above, peripheral defocus is related to a patient'sbiometric inputs, such as, for example, axial length and corneal power.Since, these parameters are also used to calculate the spherical powerof an IOL, IOLs configured to correct peripheral defocus also depend onthe foveal refractive state or the IOL spherical power to achieveemmetropia. In various embodiments of an IOL configured to compensatefor peripheral defocus in an emmetropic eye or in patients with lowamounts of myopia, the arrangement of the third set of optical featurescan provide greater amount of optical defocus in the peripheral regionsas compared to the central region. In various embodiments of an IOLconfigured to compensate for peripheral defocus, in patients withmoderate to high amounts of myopia, the arrangement of the third set ofoptical features can provide lesser amount of optical defocus in theperipheral regions as compared to the central region. In variousembodiments, the arrangement of the third set of optical features canresult in an optical power distribution that is symmetric about thecentral region. In various embodiments, the arrangement of the third setof optical features can result in an optical power distribution that isnonlinear with eccentricity. In various embodiments, the arrangement ofthe third set of optical features can result in an optical powerdistribution that varies continuously from the central region to theperipheral regions such that defocus is compensated at most or allvisual field angles. Alternately, in some embodiments, the arrangementof the third set of optical features can be configured to compensate fordefocus only at certain specific visual field angles (e.g., ±15 degrees,±20 degrees, ±25 degrees, ±30 degrees). The various operationsillustrated in method 3000 can be performed sequentially orsimultaneously. In various embodiments, the first, second and third setsof optical features can be disposed on an IOL having a base opticalpower. In various embodiments, the IOL can be designed considering thevariation of the peripheral astigmatism, peripheral defocus andhorizontal coma with respect to field of view simultaneously. In variousembodiments, the method 3000 can be iterative wherein the operations inblocks 3010, 3015, 3020 and 3025 can be repeated several times to obtainan optimized IOL power distribution that corrects for peripheral errors,such as, for example, peripheral astigmatism, horizontal coma andperipheral defocus.

Referring to FIG. 42 , in certain embodiments, a method 200 foroptimizing peripheral vision comprises an element 205 of determining oneor more physical and/or optical properties of the eye 100 including ageographical map of retinal functionality and/or the retinal shape.

The method 200 additionally comprises an element 210 of either designingor determining the type of intraocular lens 100 suitable for optimizingvisual acuity, including peripheral visual acuity. The design of thelens may be of any detailed herein, as well as modifications andalternate constructions that are apparent to a person having ordinaryskill in the art.

The method 200 also comprises an element 215 of calculating a desiredposition of the intraocular lens 100 or the optic 102 after an ocularsurgical procedure.

Referring to FIG. 43 , in certain embodiments, a computer system 300 forimproving or optimizing peripheral vision comprises a processor 302 anda computer readable memory 304 coupled to the processor 302. Thecomputer readable memory 304 has stored therein an array of orderedvalues 308 and sequences of instructions 310 which, when executed by theprocessor 302, cause the processor 302 to perform certain functions orexecute certain modules. For example, a module can be executed that isconfigured to calculate a postoperative lens position within an eyeand/or for selecting an ophthalmic lens or an optical power thereof. Asanother example, a module can be executed that is configured to performone or more of the steps in method 1700, 2200, 3100, 3000 or 200 asdescribed with reference to FIGS. 17, 22, 31, 41 and 42 respectively. Asanother example, a module can be executed that is configured todetermine an improved or optimal IOL design through the evaluation ofaberrations after a shift in the relative positions of a stop and alens, by using the stop-shift equations as described herein. As anotherexample, a module can be executed which is configured to determinebinocular IOL properties for improving peripheral contrast sensitivity.As another example, a module can be executed which is configured todetermine an optical correction which is provided to increase contrastsensitivity along the horizontal direction which can include correctionsfor astigmatism and other spherical and/or non-spherical aberrations.

The array of ordered values 308 may comprise, for example, one or moreocular dimensions of an eye or plurality of eyes from a database, adesired refractive outcome, parameters of an eye model based on one ormore characteristics of at least one eye, and data related to an IOL orset of IOLs such as a power, an aspheric profile, and/or a lens plane.In some embodiments, the sequence of instructions 310 includesdetermining a position of an IOL, performing one or more calculations todetermine a predicted refractive outcome based on an eye model and a raytracing algorithm, comparing a predicted refractive outcome to a desiredrefractive outcome, and based on the comparison, repeating thecalculation with an IOL having at least one of a different power,different design, and/or a different IOL location.

The computer system 300 may be a general purpose desktop or laptopcomputer or may comprise hardware specifically configured performing thedesired calculations. In some embodiments, the computer system 300 isconfigured to be electronically coupled to another device such as aphacoemulsification console or one or more instruments for obtainingmeasurements of an eye or a plurality of eyes. In other embodiments, thecomputer system 300 is a handheld device that may be adapted to beelectronically coupled to one of the devices just listed. In yet otherembodiments, the computer system 300 is, or is part of, refractiveplanner configured to provide one or more suitable intraocular lensesfor implantation based on physical, structural, and/or geometriccharacteristics of an eye, and based on other characteristics of apatient or patient history, such as the age of a patient, medicalhistory, history of ocular procedures, life preferences, and the like.

Generally, the instructions of the system 300 will include elements ofthe method 200, 1700, 2200, 3000, 3100 and/or parameters and routinesfor performing calculations of one or more of Equations above, such asthe stop-shift equations or the metrics.

In certain embodiments, the system 300 includes or is part aphacoemulsification system, laser treatment system, optical diagnosticinstrument (e.g, autorefractor, aberrometer, and/or corneal topographer,or the like). For example, the computer readable memory 304 mayadditionally contain instructions for controlling the handpiece of aphacoemulsification system or similar surgical system. Additionally oralternatively, the computer readable memory 304 may additionally containinstructions for controlling or exchanging data with an autorefractor,aberrometer, tomographer, and/or topographer, or the like.

In some embodiments, the system 300 includes or is part of a refractiveplanner. The refractive planner may be a system for determining one ormore treatment options for a subject based on such parameters as patientage, family history, vision preferences (e.g., near, intermediate,distant vision), activity type/level, past surgical procedures.

Conclusion

The above presents a description of the best mode contemplated ofcarrying out the concepts disclosed herein, and of the manner andprocess of making and using it, in such full, clear, concise, and exactterms as to enable any person skilled in the art to which it pertains tomake and use the concepts described herein. The systems, methods anddevices disclosed herein are, however, susceptible to modifications andalternate constructions from that discussed above which are fullyequivalent. Consequently, it is not the intention to limit the scope ofthis disclosure to the particular embodiments disclosed. On thecontrary, the intention is to cover modifications and alternateconstructions coming within the spirit and scope of the presentdisclosure as generally expressed by the following claims, whichparticularly point out and distinctly claim the subject matter of theimplementations described herein.

Although embodiments have been described and pictured in an example formwith a certain degree of particularity, it should be understood that thepresent disclosure has been made by way of example, and that numerouschanges in the details of construction and combination and arrangementof parts and steps may be made without departing from the spirit andscope of the disclosure as set forth in the claims hereinafter.

As used herein, the term “processor” refers broadly to any suitabledevice, logical block, module, circuit, or combination of elements forexecuting instructions. For example, the processor 302 can include anyconventional general purpose single- or multi-chip microprocessor suchas a Pentium® processor, a MIPS® processor, a Power PC® processor, AMD®processor, ARM processor, or an ALPHA® processor. In addition, theprocessor 302 can include any conventional special purposemicroprocessor such as a digital signal processor. The variousillustrative logical blocks, modules, and circuits described inconnection with the embodiments disclosed herein can be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA), or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.Processor 302 can be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

Computer readable memory 304 can refer to electronic circuitry thatallows information, typically computer or digital data, to be stored andretrieved. Computer readable memory 304 can refer to external devices orsystems, for example, disk drives or solid state drives. Computerreadable memory 304 can also refer to fast semiconductor storage(chips), for example, Random Access Memory (RAM) or various forms ofRead Only Memory (ROM), which are directly connected to thecommunication bus or the processor 302. Other types of memory includebubble memory and core memory. Computer readable memory 304 can bephysical hardware configured to store information in a non-transitorymedium.

Methods and processes described herein may be embodied in, and partiallyor fully automated via, software code modules executed by one or moregeneral and/or special purpose computers. The word “module” can refer tologic embodied in hardware and/or firmware, or to a collection ofsoftware instructions, possibly having entry and exit points, written ina programming language, such as, for example, C or C++. A softwaremodule may be compiled and linked into an executable program, installedin a dynamically linked library, or may be written in an interpretedprogramming language such as, for example, BASIC, Perl, or Python. Itwill be appreciated that software modules may be callable from othermodules or from themselves, and/or may be invoked in response todetected events or interrupts. Software instructions may be embedded infirmware, such as an erasable programmable read-only memory (EPROM). Itwill be further appreciated that hardware modules may comprise connectedlogic units, such as gates and flip-flops, and/or may comprisedprogrammable units, such as programmable gate arrays, applicationspecific integrated circuits, and/or processors. The modules describedherein can be implemented as software modules, but also may berepresented in hardware and/or firmware. Moreover, although in someembodiments a module may be separately compiled, in other embodiments amodule may represent a subset of instructions of a separately compiledprogram, and may not have an interface available to other logicalprogram units.

In certain embodiments, code modules may be implemented and/or stored inany type of computer-readable medium or other computer storage device.In some systems, data (and/or metadata) input to the system, datagenerated by the system, and/or data used by the system can be stored inany type of computer data repository, such as a relational databaseand/or flat file system. Any of the systems, methods, and processesdescribed herein may include an interface configured to permitinteraction with users, operators, other systems, components, programs,and so forth.

What is claimed is:
 1. An intraocular lens configured to improve visionfor a patient's eye, the intraocular lens comprising: an opticcomprising a first surface and a second surface opposite the firstsurface, the first surface and the second surface intersected by anoptical axis, wherein the first or the second surface of the optic isaspheric, wherein the optic is configured to focus light incident alonga direction parallel to the optical axis at a fovea to produce afunctional foveal image and that is configured to focus light incidenton the patient's eye at an oblique angle with respect to the opticalaxis at a peripheral retinal location disposed at a distance from thefovea, the peripheral retinal location having an eccentricity between 1and 30 degrees, wherein the optic is a meniscus lens having a concaveanterior surface with negative optical power, a convex posterior surfacewith positive optical power, and a shape factor between minus 4 andminus 1.5, wherein the shape factor is equal to the sum of an anterioroptical power and a posterior optical power divided by the differencebetween the posterior optical power and the anterior optical power,wherein image quality at the peripheral retinal location is improved byreducing at least one optical aberration at the peripheral retinallocation, wherein the at least one optical aberration is selected fromthe group consisting of defocus, peripheral astigmatism and coma.
 2. Theintraocular lens of claim 1, wherein the oblique angle is between about1 degree and about 30 degrees.
 3. The intraocular lens of claim 1,wherein the foveal image has a modulation transfer function (MTF) of atleast 0.5 at a spatial frequency of 100 cycles/mm for both thetangential and the sagittal foci in green light for a pupil size between3-5 mm.
 4. The intraocular lens of claim 1, wherein an image formed atthe peripheral retinal location has a figure of merit of at least 0.5,wherein the figure of merit is an average MTF for a range of spatialfrequencies between 0 cycles/mm and 30 cycles/mm obtained at differenteccentricities between 1 and 30 degrees.
 5. The intraocular lens ofclaim 1, wherein the first surface or the second surface comprises aplurality of optical features that are configured to reduce the at leastone optical aberration.
 6. The intraocular lens of claim 1, wherein themeniscus lens has a vertex curving inwards from edges of the optic. 7.The intraocular lens of claim 1, wherein the optic has a thicknessbetween about 0.3 mm and about 2.0 mm.
 8. The intraocular lens of claim1, further comprising a second optic separated from the optic by adistance.
 9. The intraocular lens of claim 8, wherein the distancebetween the optic and the second optic is fixed.
 10. The intraocularlens of claim 8, wherein the distance between the optic and the secondoptic is varied by application of ocular forces.
 11. The intraocularlens of claim 8, wherein the optic is configured to be disposed in thecapsular bag of the patient's eye, and the second optic is configured tobe disposed between the iris and the capsular bag of the patient's eye.12. The intraocular lens of claim 8, wherein the optic and the secondoptic are both configured to be disposed in the capsular bag of thepatient's eye.
 13. The intraocular lens of claim 1, wherein the optic isconfigured to improve image quality at the peripheral retinal locationby adjusting the shape factor of the optic that reduces the at least oneoptical aberration.
 14. The intraocular lens of claim 13, wherein theshape factor of the optic is adjusted by adjusting a parameter of theoptic, the parameter selected from the group consisting of a curvatureof the first surface or the second surface, an axial position of theoptic with respect to the retina and a thickness of the optic.